Bible study notes on the topic of sex, marriage and related topics.

Sexual Immorality

General term used in New Testament. Greek word πορνεία (porneia) means literally prostitution. But also more broadly can refer to all sexual immorality, including fornication.

Proverbs 31:3 Do not give your strength to women.
Matthew 15:19 Out of the heart come evil thoughts, including sexual immorality (NKJV "fornications").
1 Corinthians 5:1-2 Sexual immorality—in this case, specifically someone "having" his father's wife.
1 Corinthians 6:9 Fornicators from Greek πόρνος (pornos) (male prostitutes maybe) won't inherit the kingdom.
1 Corinthians 6:12-20 Flee sexual immorality. Don't be joined to a prostitute.
1 Corinthians 6:16 The word "harlot" is translated from πόρνη (pornē).
1 Corinthians 6:18 He who commits sexual Immorality sins against his own body. "Sexual Immorality" is translated from πορνεία (porneia).
1 Corinthians 7:2 In some regards, it's good for people to stay single, but because of sexual Immorality, it's good to get married. "Sexual Immorality" is translated from πορνεία (porneia).
Galatians 5:19 Sexual immorality (NKJV "fornication") is listed as one of the works of the flesh.
Ephesians 5:3-7 Don't let fornication be even named among you. Fornicators won't inherit the kingdom. Wrath of God comes on such people.
1 Thessalonians 4:3-8 Abstain from sexual immorality, lust.
1 Timothy 1:10 The law is made for sinners such as sexually immoral.
Hebrews 13:4 Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge.
Revelation 21:8 Sexually immoral are among those thrown into the lake of fire.

Fornication, Pre-marital Sex

See the notes above regarding sexual immorality and the Greek word πορνεία (porneia). A lot of that is relevant to fornication.

Genesis 34 Dinah incident. The sound of this seems to be, not rape but pre-marital sex. It is described as a shameful thing that Shechem did, not ameliorated by his desire to marry her.
Exodus 22:16-17; Deuteronomy 22:28-29 Man who lies with a virgin not betrothed or married. He must marry her. Some say this is forcing a woman to marry her rapist. But that's a misreading of meaning. Compare Ex says "entices" while Deut says "seizes".
Deuteronomy 22:13-21 Blood on the wedding sheets as evidence of a woman's virginity. Death penalty for a woman who is not a virgin as expected. Described as "played the harlot".
1 Corinthians 7:2,9

Adultery

Genesis 39:6-20 Joseph refused to sleep with his master's wife.
Exodus 20:14; Deuteronomy 5:18; Matthew 19:18; Mark 10:19; Luke 18:20 Seventh commandment.
Leviticus 18:20; 20:10 Death penalty for adultery.
Numbers 5:11-31 Ritual for wife suspected of adultery.
Deuteronomy 22:22 Death penalty for both man and woman.
Deuteronomy 22:23-27 Also for betrothed. Note the asymmetry between rules for man and woman (men perpetrate rape on a woman victim). Leviticus 19:20 Only a scourging for the case of a betrothed concubine (a woman who is not free — see section below re concubines).
2 Samuel 11 David committed adultery with Bathsheba, wife of Uriah.
Proverbs 2:16-19 Seductress forsakes her marriage covenant, and leads men to death.
Proverbs 5
Proverbs 6:23-35 God's commands keep us from the evil woman, seductress, harlot, neighbour's wife. v.32 Whoever commits adultery lacks understanding; destroys his own soul.
Proverbs 7:4-27 Beware of the seductress, harlot, adulteress.
Proverbs 9:13-18 Beware of the foolish woman.
Jeremiah 3:8-9 Adultery symbolic of spiritual unfaithfulness to God.
Jeremiah 5:7-9; 13:27 Israel committed idolatry, adultery, harlotry.
Ezekiel 18:6,11,15; 22:11; 33:26 God criticises Israel for defiling one another's wives.
Matthew 1:18-25 Joseph and Mary, betrothed but marriage not yet consummated. Shows Joseph's attitude to laws about sex and marriage.
Matthew 5:27-30 Jesus magnified the law: even to look lustfully is to commit adultery.
Matthew 5:31-32; 19:9; Mark 10:11-12; Luke 16:18 Divorce causes adultery.
John 8:3-11 Woman caught in adultery, brought to Jesus to ask what he thought should be done. He said, “Neither do I condemn you; go and sin no more.”
Romans 13:9 The commandments, including that for adultery, are based in "love your neighbour as yourself".
Hebrews 13:4 Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge.

Marriage

Genesis 2:18-25 Institution of marriage began with Adam and Eve. "It is not good that man should be alone. I will make him a helper comparable to him… They shall become one flesh". Quoted by Jesus in Matthew 19:5-6; Mark 10:7-9.
Deuteronomy 24:5 A man is free from war and business duties for one year after getting married, to bring happiness to his wife.
Proverbs 2:17 Marriage is a covenant of God. See also Malachi 2:14.
Proverbs 5:18-19 Sexual relationship in marriage is blessed.
Proverbs 18:22 A wife is a blessing.
Malachi 2:14 Marriage is a covenant of God. See also Proverbs 2:17.
Matthew 19:6 "…what God has joined together, let no man separate." God joins a man and woman together in marriage.
Romans 7:1-3 Marriage is for life, "'til death do us part". After death of spouse, remarriage is fine.
1 Corinthians 7:3-5 Sexual duties between husband and wife.
1 Corinthians 7:1-2,6-9 Is it good not to marry?
1 Corinthians 7:25-35 Perhaps in a time of persecution, pragmatically better not to marry.
1 Corinthians 7:32-35 Benefits to not marrying: more devotion to pleasing God.
Ephesians 5:22-33 Principles of marriage for husband and wife.
Ephesians 5:32; Revelation 12:1; 19:7-9 Marriage is symbolic of Christ and the church.
1 Timothy 4:3 "forbidding to marry" is a false doctrine.
1 Timothy 4:11-14 Encourage younger widows to remarry.
Hebrews 13:4 Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge.

Practical Protections of Marriage

The Biblical rules provide various practical, financial protections in the marriage covenant. The protections are for the wife and for the children.

Deuteronomy 25:5-6 Levirate marriage.
Matthew 5:32
Mark 10:2-12
Romans 7:2
Hebrews 13:4
Ephesians 5:22-25; 6:4
1 Timothy 5:8

Minimum age

A minimum age of marriage isn't given. Various scriptures seem to imply there was a practical expectation that someone should reach physical maturity, though it's not precisely ruled.

Genesis 38:11,14 Judah wanted his son Shelah to marry Tamar once he was "grown".
Ruth 1:11-13 Naomi talking about her bereaved daughters-in-law not wanting to wait for Naomi to have sons that were "grown" for them to marry.
Ezekiel 16:7-8 in a marriage metaphor of God's relationship with Israel, metaphorically talks about puberty and reaching "the time of love".

Marriage Provides for Children to Learn Righteousness

Genesis 18:19 Abraham.
Exodus 20:12; Deuteronomy 5:16; Ephesians 6:1-4; Colossians 3:18-21 Children obey parents, the commandment with promise. Fathers, love children and raise them well in God.
Proverbs 22:6 Teach up a child…
Malachi 2:15 God seeks godly offspring.
Malachi 4:6 Elijah to come who will turn the hearts of the fathers to the children, and vice-versa.

Arranged/Forced Marriage

Genesis 2:18-25 Adam and Eve were effectively a marriage arranged by God.
Genesis 24:1-67 Isaac's marriage to Rebekah. He didn't even get to meet her before the marriage was decided. Genesis 24:5-8,39-41,49,57-58 Arranged but not forced. Rebekah was able to decide whether or not to go.
Genesis 29:20-30 Jacob's marriage to Leah was a fraudulently arranged and forced marriage.
Genesis 41:45 Joseph and Asenath.
Exodus 2:21 Moses and Zipporah.
Exodus 21:4 A master might give his servant a wife. (The woman and any children would remain the property of the master once the male servant left.)
Exodus 21:7-11 A man might sell his daughter as a "female slave". Implication is for marriage to the buyer, or an arranged marriage to a son of the buyer.
Numbers 31:17-18 The Israelites were permitted to keep virgin Midianite girls alive for themselves.
Deuteronomy 20:14-16; 21:10-14 Taking a wife from among captives of war.
Joshua 15:16-17; Judges 1:12-13 Caleb promised his daughter Achsah in marriage to whoever would capture Kirjath Sepher.
Judges 12:9 Ibzan brought in 30 daughters from elsewhere to marry his 30 sons.
Judges 21 Israel's efforts to provide wives for the remaining men of Benjamin, after nearly destroying the whole tribe. They took virgins from Jabesh Gilead after killing everyone else. Also they arranged for Benjaminites to snatch women from a local festival at Shiloh.
1 Samuel 18:17-19 Saul offered his daughter Merab to David to marry. But David politely declined. Then she was given to another man instead.
1 Samuel 18:20-29 Saul gave his daughter Michal to David. Note, it was known Michal loved David, so it wasn't a loveless marriage.

Female Consent

Genesis 24:5-8,39-41,57-58 Rebekah was free to decide whether to go to marry Isaac or not. Though she didn't have an opportunity to meet him first. There was strong indication that God's hand was providential, so that probably gave her confidence.
Numbers 36:6 Zelophehad's daughters were told they could marry whom they thought best, with the caveat that he must be of their tribe.
1 Corinthians 7:12-15 If an unbelieving wife is not willing to stay with a believing husband, let her depart.

Female Rights

Exodus 21:10 says a man must provide his wife's "marriage rights".
1 Corinthians 7:3-5 says a man must provide the affection due to his wife, and vice-versa.

Levirate Marriage

This law describes how if a man dies without children, his brother (or other close relative) should marry his widow and raise a child for the man who died, to perpetuate his inheritance.

Genesis 38:8-11,14 Levirate marriage for Er's wife Tamar.
Deuteronomy 25:5-10 Levirate marriage law.
Ruth 1:12-13; 3:2,9,12; 4:5-10 Ruth's story of marriage to Boaz involves this law.
Matthew 22:23-30; Mark 12:18-27 Sadducees asked Jesus about a scenario related to this law, to try to make a point against teaching of resurrection.

Polygamy

Genesis 4:19 First case: Lamech who married Adah and Zillah.
Genesis 25:6 Abraham had concubines.
Genesis 29:15-35; 30:1-24 Jacob married Leah as well as Rachel, due to Laban's trickery. The wife-sisters' rivalry was bitter.
Genesis 31:50 Laban considered it would be wrong if Jacob were to marry any more wives besides Laban's daughters.
Exodus 2:21; Numbers 12:1 Moses married two women.
Exodus 21:10 "If he takes another wife…" implicitly permits polygamy, with conditions (don't show favouritism to one wife).
Leviticus 18:18 God prohibited marrying two sisters, mentioning rivalry.
Deuteronomy 17:17 A king must not "multiply wives for himself, lest his heart turn away". 1 Kings 10:26-29; Nehemiah 13:26 But Solomon did.
Deuteronomy 21:15-17 Laws of inheritance — firstborn double-portion birthright — in the case of someone who has married more than one wife, and favours one over the other.
Judges 8:30 Gideon had many wives.
1 Samuel 1:1-7 Samuel's father Elkanah had two wives Peninnah and Hannah, and Peninnah provoked Hannah.
2 Samuel 5:13; 1 Chronicles 3:9; 14:3-7 David had multiple wives and concubines.
1 Kings 11:3 Solomon had seven hundred wives, princesses, and three hundred concubines.
2 Chronicles 11:21 Rehoboam had 18 wives and 60 concubines.
1 Timothy 3:2 An overseer must be "the husband of one wife". Does this mean to prohibit polygamy, or divorce, or remarriage in general?

Surrogacy

Genesis 16:1-16 Sarai asked Abram to have sex with her maid Hagar. "Perhaps I shall obtain children by her." The text says Sarai gave her to her husband "to be his wife". The story shows this caused conflict and complications, and isn't endorsed by God. Hagar and Ishmael ultimately left Abraham, in Genesis 21:8-21.
Genesis 30:3-4 Rachel and Bilhah. Rachel gave her maid to her husband "as wife".
Genesis 30:9,18 Leah and Zilpah. Leah gave her maid to Jacob "as wife".

These cases describe surrogate motherhood. In each case it involves a maid of the woman. Somehow the resulting children are regarded as belonging to the woman. The woman gives her maid "as wife". Reading between the lines, this is regarded as involving a sacrifice on the part of the woman (giving her maid into the embrace of her husband). Being given "as wife" implies a long-term commitment, not a brief agreement, although in Hagar's case she did later leave Abraham.

Levirate marriage (see above) is conceptually surrogate fatherhood.

Concubine

Genesis 22:24 Abraham's brother Nahor's concubine Reumah.
Genesis 25:1-6 describes Keturah as Abraham's wife, but says Abraham gave all that he had to Isaac, but says he gave gifts to the sons of his concubines. 1 Chronicles 1:32 describes Keturah as Abraham's concubine.
Genesis 35:22 Bilhah is described as Jacob's concubine. Genesis 29:29 Bilhah was Rachel's maid given to her by her father Laban. Genesis 30:1-7; 37:2 She is described as being given to Jacob by Rachel "as wife". (This is similar to Abram and Sarai and Hagar in Genesis 16:3. Ishmael is described as being a son "by a bondwoman" in Galatians 4:22, symbolic of bondage of the Old Covenant.) But Genesis 32:22 says Jacob had 2 wives and 2 female servants.
Genesis 36:12 Timna was the concubine of Eliphaz, Esau's son.
Exodus 21:7-11 Some describe this as a sort of concubine arrangement. Purchasing someone's daughter to be a wife.
Exodus 22:16-17 In the laws for sex outside marriage, mentions a "bride-price for her to be his wife"; a "bride-price for virgins". Is this the same or different from Exodus 21:7-11? Probably different, because there is no economic reason to think she would not still be a free woman.
Leviticus 19:20-22 The penalty for sexual relations with someone's betrothed concubine was a scourging, not death, "because she was not free". But it is still described as a sin for the man.
Numbers 31:18; Deuteronomy 21:10-14 Taking a wife from among captives of war. If you have no delight in her, set her free, but don't sell her, or treat her brutally, because you have humbled her.
Judges 8:31 Abimelech son of Gideon's concubine in Shechem. Judges 9:1-3 Evidently was not considered a son at the same level as Gideon's 70 sons (in some sense). Killed all of Gideon's sons bar one, and made himself king in Shechem. Judges 9:18 calls Abimelech "the son of [Gideon's] female servant".
Judges 19; 20 The story of the Levite's concubine. Judges 20:4-6 describes the Levite as the husband of his concubine.
2 Samuel 3:7; 21:11 Saul's concubine Rizpah.
2 Samuel 5:13; 15:16; 16:21-22; 19:5; 20:3 David's concubines. He left ten when he fled from Absalom. Absalom slept with them, apparently fulfilling 2 Samuel 12:11 which said "wives". After that David had no more sexual relations with them, but they lived as widows. 1 Chronicles 3:9 mentions that David's concubines had sons, but doesn't name them.
1 Kings 11:3 Solomon had seven hundred wives, princesses, and three hundred concubines; and his wives turned away his heart. Song of Solomon 6:8-9 says 60 queens and 80 concubines and virgins without number.
1 Chronicles 2:46-49 lists descendants of two of Caleb's concubines, Ephah and Maachah. (Caleb son of Hezron, not the famous Caleb son of Jephunneh of Numbers 13:6; 32:12 etc.)
1 Chronicles 7:14 Manasseh had a Syrian concubine, whose descendants are listed.
2 Chronicles 11:21 Rehoboam had 18 wives and 60 concubines.
Esther 2:14 Shaashgaz kept King Ahasuerus' concubines.
Daniel 5:2-3,23 mentions Belshazzar's concubines.

Marry a Believer

Genesis 24:1-4 Abraham told Isaac not to marry a Caananite woman.
Genesis 28:1 Isaac told Jacob not to marry a Caananite woman.
Genesis 26:34-35; 28:6-9; 36:2 Esau had married Caananite (Hittite) women, but saw it displeased his parents. So he married a daughter of Ishmael as well.
Exodus 34:11-16 Don't intermarry (or make any other agreement) with pagans of the land, and consequently "play the harlot" with their gods.
Leviticus 19:19; Deuteronomy 22:9-11 Principle of not mixing things that don't go together, including "don't plow with an ox and a donkey together".
Numbers 31:12-18 Moses rebuked the Israelites for keeping alive women of Moab who had previously caused them to sin in pagan rites. But he allowed them to keep alive young Moabite girls who were virgins.
Deuteronomy 21:10-14 Taking a wife from among captives of war. But only from nations far away, not from the Canaanites who God said are too idolatrous and morally corrupt.
Deuteronomy 7:1-5; 22:10; 23:2 Don't marry pagans who will turn us away from God.
Judges 3:5-6 The Israelites married Canaanites and were influenced to worship Canaanite gods.
Judges 14; 16 Samson had a lot of upheaval in his life as he desired Philistine women. Conflict at his wedding to a Philistine woman. Went in to a Philistine harlot. Was betrayed by Delilah.
Ruth 1:1-18 Ruth was a Moabite, but one who trusted in God. Matthew 1:5 Ruth was in the genealogy of Christ.
1 Kings 11:1-13 King Solomon married many foreign wives, from the nations God warned Israel not to marry with. They turned his heart away from God, influencing him to engage in idolatry.
1 Kings 16:30-33; 21:25 Ahab was wicked, more-so due to the influence of his pagan wife Jezebel.
2 Chronicles 19:2 A prophet to Jehoshaphat: “Should you help the wicked and love those who hate the Lord? Therefore the wrath of the Lord is upon you.” (the principle, though not about marriage in this case)
2 Kings 8:16-18,26-27; 2 Chronicles 18:1; 21:6; 22:2 Jehoram son of Jehoshaphat was evil, in part due to the influence of his wife Athaliah who was a daughter of Ahab. 2 Kings 8:26-27 This also influenced his son Ahaziah to do evil.
Ezra 9; 10 Ezra had to deal with people of Judah who married foreigners. Ezra 9:2 criticises marriages with Canaanites, saying "the holy seed is mixed with the peoples of those lands." Ezra 9:11 says the issue was about the wickedness of those nations.
Nehemiah 10:30; 13:23-30 Jews who had married pagans. Their children didn't even speak Judah's native language. Pagan women even caused Solomon to sin.
Amos 3:3 Can two walk together, unless they are agreed?
Malachi 2:10-12 Judah has done treacherously, an abomination, by marrying the daughter of a foreign god. May God cut off such a person from Jacob.
1 Corinthians 7:39 Marry "only in the Lord".
1 Corinthians 15:33 Evil company corrupts good habits.
2 Corinthians 6:14-18 Principle of "Don't be unequally yoked". Don't join together believers and unbelievers in an intimate union. May also apply to business ventures, friendships, military service, alliances (eg Jehoshaphat in 2 Chronicles 19:2).
James 4:4 Adulterers and adulteresses! Do you not know that friendship with the world is enmity with God? Whoever therefore wants to be a friend of the world makes himself an enemy of God.

Apparent counter-examples

Genesis 38:2 Judah married a daughter of Shua, a Canaanite.
Genesis 41:45 Joseph married Asenath, the daughter of Potiphera priest of On.
Exodus 2:16-22 Moses married Zipporah daughter of Jethro "priest of Midian". Exodus 18:8-12 indicates that Jethro was favourable towards God — to a certain degree of understanding.
Numbers 31:12-18 Moses rebuked the Israelites for keeping alive women of Moab who had previously caused them to sin in pagan rites. But he allowed them to keep alive young Moabite girls who were virgins.
Deuteronomy 21:10-14 Taking a wife from among captives of war. But only from nations far away, not from the Canaanites who God said are too idolatrous and morally corrupt.
Joshua 6:17-25 Rahab the harlot, of Jericho, must have been a Canaanite. Matthew 1:5 Salmon begot Boaz by Rahab, thus Rahab was in the lineage of Jesus.
Ruth 1:4 Ruth was a Moabite, and eventually married Boaz. Thus Ruth was in the lineage of Jesus.
Esther became queen to a Gentile king. God used her in the protection of His people.

Interracial Marriage

See "Marry a Believer" section above. The key issue seems to be about religious fidelity, not race.

Genesis 16:1-4; 25:12 Abram went in to Hagar, Sarai's Egyptian maidservant.
Genesis 41:45 Joseph married Asenath, the daughter of Potiphera priest of On. Presumably she was Egyptian. Though, if Joseph and Moses could passably "fit" with Egyptian society (Joseph was unrecognised by his own brothers), maybe there wasn't an obvious racial disparity.
Numbers 12:1 Aaron and Miriam spoke against Moses for marrying an Ethiopian (Cushite) woman. Apparently she was a second wife, because his first, Zipporah in Exodus 2:21, was a Midianite.
Joshua 6:17-25 Rahab the harlot, of Jericho, must have been a Canaanite. Matthew 1:5 Salmon begot Boaz by Rahab, thus Rahab was in the lineage of Jesus.
Ruth 1:4 Ruth was a Moabite. Genesis 19:36-37 The Moabites were descendants of Lot. So not really inter-racial marriage. Matthew 1:5 Ruth was in the genealogy of Christ.
1 Kings 3:1; 7:8; 9:24; 2 Chronicles 8:11 Solomon married the Egyptian Pharaoh's daughter.
Ezra 9:2 criticises marriages with Canaanites, saying "the holy seed is mixed with the peoples of those lands." But Ezra 9:11 says the issue was about the wickedness of those nations.
Acts 17:26 All humans are from one blood (Adam).
Acts 10:34; Romans 2:11 God shows no partiality.
Romans 10:12-13; Galatians 3:28; Colossians 3:11 There is neither Jew nor Greek…

Divorce

Genesis 2:18-25 Institution of marriage began with Adam and Eve. "They shall become one flesh". Quoted by Jesus in Matthew 19:5-6; Mark 10:7-9.
Deuteronomy 22:19 Divorce not permitted after a man brings a false accusation of sexual infidelity against his wife.
Deuteronomy 22:29 Divorce not permitted after a man has pre-marital sex with a woman. (Is this a rape scenario?)
Deuteronomy 24:1-4 Old Testament law on divorce. Send her out with a certificate. Not allowed to remarry her again later.
Proverbs 5:15-20 Rejoice with the wife of your youth.
Ecclesiastes 9:9 Live joyfully with the wife you love all the days of your vain life…
Jeremiah 3:1,8 God uses metaphor of divorce and returning to refer to His people.
Malachi 2:13-16 God wants godly offspring. Don't deal treacherously with one's wife, "your companion and your wife by covenant". Divorce covers your garment with violence.
Matthew 5:31-32; Luke 16:18 Don't divorce, except due to sexual immorality. To divorce and remarry is to commit adultery, and cause your spouse to commit adultery. Likewise to marry a divorcee.
Matthew 19:3-10; Mark 10:2-12 Jesus's appeal to not separate what God had joined. Divorce was only ever permitted due to "the hardness of your hearts", but was never God's will. Divorce causes adultery.
Romans 7:2 A woman who has a husband is bound by the law to her husband as long as he lives. But if the husband dies, she is released from the law of her husband.
1 Corinthians 7:10-11 A wife should not divorce. But if you do separate, stay unmarried or reconcile. A husband should not divorce. (Are the rules stricter for men—ie simply "don't divorce"—or is it just ambiguous wording?)
1 Corinthians 7:12-16 Divorce principles in the case of unbelievers. Don't divorce an unbelieving spouse if they're willing to live in peace. Unbelieving spouse is sanctified. But if they depart, believer is not bound.
1 Corinthians 7:39 Wife is bound as long as her husband lives.

Sex for Pleasure

Sex for pleasure is blessed within the marriage relationship.

Genesis 2:18-25 "…they shall become one flesh…"
Proverbs 5:18-19 Rejoice with the wife of your youth… let her breasts satisfy you…
Song of Solomon 4 Description of sexual pleasure in marriage.
1 Corinthians 7:3-9 Practical guidelines for fulfilling the spouse's sexual desires.
Hebrews 13:4 The marriage bed is honourable and undefiled.

Rape

Genesis 19:30-38 Lot's daughters made him drunk then had sex with him.
Genesis 34 Case of Dinah and Shechem doesn't sound like rape, due to v.3-4, even though v.2 uses same Hebrew word as 2 Samuel 13:14 translates "forced".
Genesis 39:7-20 Joseph was unjustly accused of a rape attempt, by his master's wife.
Deuteronomy 22:25-27 Law about rape, which is assumed for case of a married or betrothed woman in a remote setting. In a populated area where she could cry out with reasonable expectation of being heard, that sex is considered as adultery.
Exodus 22:16-17; Deuteronomy 22:28-29 Man who lies with a virgin not betrothed or married. He must marry her. Some say this is forcing a woman to marry her rapist. But, the mandate is upon the man—to look after the woman he humbled. Ex says "entices" while Deut says "seizes".
Judges 19; 20 The Levite's concubine, raped by men of Gibeah. The Levite and his host both seem grossly heartless in their failure to provide her care and safety, while later being outraged at what the men of Gibeah did to her.
2 Samuel 13:1-22 Amnon raped Tamar. His desire for her almost immediately turned to disdain for her after he raped her.

War-time Rape by Enemies

Deuteronomy 28:30 Curses on disobedience.
Judges 5:30
Isaiah 13:16
Jeremiah 8:10
Lamentations 5:11
Zechariah 14:2

Homosexuality

Genesis 19:5 Men of Sodom wanted homosexual sex.
Leviticus 18:22; 20:13 Prohibited.
Judges 19:14-25
1 Samuel 18:1-4; 19:1; 20:3,17,41; 2 Samuel 1:25-26 Some have claimed that this describes a homosexual relationship between David and Jonathan.
Matthew 19:12 eunuchs born that way.
Romans 1:26-29 God gave up ungodly people to chase unnatural and wrong desires.
1 Corinthians 6:9 Homosexuals (amongst others including thieves, idolaters and covetous people) won't inherit the kingdom.
1 Corinthians 7:2 Because of sexual immorality, let each man have his own wife, and each woman her own husband.
1 Timothy 1:10 homosexuals are among sinners for whom the law is written.
Jude 1:7 Sodom and Gomorrah, who went after sexual immorality, set as an example of God's judgement.

Cross-dressing

Deuteronomy 22:5 Women must not wear men's clothing, and vice-versa. It's an abomination to God.
1 Corinthians 11:4-15 Women wearing a covering; hair length. Somewhat puzzling what issue exactly is being discussed, and the context of the issue, and the Old Testament law basis for what Paul writes.

Trans-gender or Intersex

Matthew 19:12 eunuchs born that way.

Emasculation

Deuteronomy 23:1 He who is emasculated by crushing or mutilation shall not enter the assembly of the Lord.
Isaiah 39:7 Prophecy given to Hezekiah about Judah going into captivity and some becoming eunuchs.
Isaiah 56:3-5 Post-exile, God reassures eunuchs (and Gentiles) that they have a place in His kingdom.
Daniel 1:3 Daniel and his friends were put under the "master of his eunuchs". Were they made eunuchs? The Hebrew word can mean government official. Eg Genesis 39:1 Potiphar was called an officer—same word as eunuch—but was married. But see Isaiah 39:7; 56:3-5 as listed above.

Matthew 19:12 eunuchs born that way; eunuchs made that way by men.

Beastiality

Leviticus 18:23; 20:15-16 Prohibited.
Deuteronomy 27:21 Cursed.

Close Relatives

Genesis 19:30-38 Lot's daughters made him drunk then had sex with him. (Not to be read as an endorsement, but as a regrettable event.)
Leviticus 18:6-18; 20:11-21 prohibits sexual relations with various close relatives. Even some that had previously been done, eg by Abraham marrying his half-sister: Genesis 20:2,12
Deuteronomy 27:20-23 Cursed.
Ezekiel 22:11 God criticises Israel for engaging in relations with close relatives, as well as adultery.
Amos 2:7 A man and his father go in to the same girl.
1 Corinthians 5:1 Sin in church at Corinth — a man had his father's wife.

Prostitution

See the notes above regarding sexual immorality and the Greek word πορνεία (porneia). The Greek word literally means prostitution, so a lot of the scriptures about "sexual immorality" are relevant to prostitution.

Genesis 34:31 Jacob's sons regarding Shechem and Dinah: "Should he treat our sister like a harlot?"
Genesis 38 Judah and Tamar. Tamar dressed as a harlot, and Judah went in to her. His hypocrisy was exposed.
Leviticus 19:29 Do not prostitute your daughter, making her be a harlot. That would make the land fall into harlotry and be full of wickedness.
Judges 16:1 Samson went in to a harlot at Gaza. The Bible makes no explicit statement condemning his actions, but the rest of scriptures should make it clear it was wrong.
Proverbs 2:16-19 Beware of the seductress.
Proverbs 6:23-35 God's commands keep us from the evil woman, seductress, harlot, neighbour's wife.
Proverbs 7:6-27 Beware of the seductress, harlot, adulteress.
Proverbs 9:13-18 Beware of the foolish woman.
Proverbs 23:27-28 A harlot is a deep pit.
Proverbs 29:3 A companion of harlots wastes his wealth.
1 Corinthians 6:12-20 Flee sexual immorality. Don't be joined to a prostitute.
Revelation 17:1,5,16-17 Babylon is described as a harlot that rides the beast.

Pornography

English word is derived from Greek πορνεία (porneia). Pornography is like visual prostitution.

Job 31:1 Job determined not to look at a woman lustfully.
Proverbs 6:25 Don't lust after a seductive woman in your heart.
Matthew 5:27-30 Jesus magnified the law of adultery: even to look lustfully is to commit adultery.

Masturbation

Genesis 38:8-10 Onan's sin is not masturbation, but using coitus interruptus to avoid carrying out his duty to his brother (kindred redeemer aka levirate marriage).
Leviticus 15:16-18; 22:4-7 Laws of uncleanness due to emission of semen. Note normal sexual intercourse between man and wife also makes them unclean. Unclean doesn't mean sin in its own right, but is ceremonial for purity when going to the tabernacle (Lev 15:31).
Deuteronomy 23:9-11 Strict rules for soldiers going to war and "some occurrence in the night". God expected the army to be holy.
Proverbs 5:18-19 Be satisfied by your wife.
1 Corinthians 6:12 Don't be ruled by desire.
1 Corinthians 7:1-5 Sexually satisfy your spouse, to fend off Satan's temptations due to lack of self-control.
2 Corinthians 10:5 Bring every thought into captivity.

Lust and Temptation

Matthew 5:29-30 Do whatever is required to resist our temptations. Some small sacrifice is better than losing our salvation.
Romans 8:1-11 Live by God's spirit, not by our fleshly desires.
Romans 13:13 Let us walk properly, as in the day, not in revelry, drunkenness, lewdness, lust…
1 Corinthians 7:2,5-9
1 Corinthians 10:13 God doesn't give us temptations that are too much for us to endure.
2 Corinthians 10:5 Bring every thought into captivity.
Galatians 5:16-25 Walk in the spirit, and you will not fulfill the lust of the flesh.
Ephesians 4:17-24 Put off life of lusts, and put on a new man led by God's spirit.
James 1:12-15 Blessed to endure temptation. Temptation arises from our own desires.
1 Peter 2:11 …as sojourners and pilgrims, abstain from fleshly lusts which war against the soul.
1 Peter 4:1-6 Resist sin and our human desires, even while people around us live by lusts.
2 Peter 2:10,18-19
1 John 2:15-17 This world motivated by lust of the eyes, lust of the flesh, pride of life.

Sexual Practices in Idolatry

Often pagan idolatry involved some sexual behaviour.

Genesis 38:21-22
Exodus 32:6; 1 Corinthians 10:7 Revelry at golden calf incident.
Numbers 25:1-9; 31:16; 1 Corinthians 10:8; Revelation 2:14 Balaam and the Moabites. The people "committed harlotry" with the women of Moab, and attended the sacrifices of the Moabite gods.
Deuteronomy 23:17
1 Kings 14:24; 15:12; 22:46
2 Kings 23:7
Hosea 4:14

Spiritual Symbolism of Sexuality

Harlotry, adultery, fornication etc used as a metaphor for spiritual unfaithfulness to God. But on the flip side, marriage is a symbol of faithfulness to God.

Exodus 34:15-17 warns against "playing the harlot" with Canaanite gods, and intermarrying with them.
Leviticus 20:6 Someone who "prostitutes" themselves with mediums or familiar spirits.
Psalm 45 Messianic marriage psalm.
Psalm 106:39
Proverbs 23:28 Harlotry "increases the unfaithful among men". Marriage is an institution of lifelong faithfulness to the marriage partner. It is thus a metaphor of spiritual faithfulness.
Isaiah 54:5
Isaiah 57:7-10
Jeremiah 2:20-25,32-37; 3:1-9 Harlotry & adultery = idolatry.
Jeremiah 3:20-22 Israel was like a wife who treacherously departs from her husband.
Jeremiah 31:32 Israel broke their covenant with God, even though He was like a husband to them.
Ezekiel 6:9 Adultery and harlotry with idols.
Hosea 1:2 The land has committed great harlotry by departing from the Lord.
Hosea 2:2-20 symbolism of harlotry of Israel, followed by God restoring a marriage covenant with His nation.
Hosea 3:1-5 Hosea told his harlot wife to stop playing the harlot. Return to marriage covenant faithfulness.
Hosea 4:11-19 Harlotry and Israel's idolatry.
2 Corinthians 11:2 I have betrothed you to one husband, that I may present you as a chaste virgin to Christ.
Ephesians 5:22-33 Marriage is a symbol of the relationship between Christ and the church.
Revelation 14:4 The 144,000 are described as "virgins, not defiled with women".
Revelation 17:1,5,16-17 Babylon is described as a harlot that rides the beast.
Revelation 19:6-9 Marriage supper of the Lamb. Bride's clean white linen is the righteous acts of the saints.
Revelation 21:2,9 New Jerusalem is described as the bride, the Lamb's wife.

Love

Despite the saying, "love is love", sex and love are different things. It is possible to have sex without love. Conversely, love does not require sex.

1 Corinthians 13 Love chapter.
Ephesians 5:22-33 Wives submit to husbands; husbands love your wives.

Ceremonial Uncleanness

Exodus 19:15 Before God appeared at Mt Sinai, Moses told the people to get ready, including washing their clothes and staying away from their wives.
Leviticus 12:1-8 Uncleanness due to childbirth, similar to menstruation. 33 days for a baby boy, 66 days for a baby girl. No explanation why it is double time for a female child.
Leviticus 15:16-17,32; 22:4-7 Uncleanness due to emission of semen. Wash body with water and be unclean until evening.
Leviticus 15:18 Uncleanness due to emission of semen during normal sexual intercourse between man and wife.
Leviticus 15:19-33 Uncleanness due to menstruation or other unusual discharge.
Leviticus 15:31 Unclean doesn't mean sin in its own right, but is ceremonially symbolic for purity when going to the tabernacle.
Deuteronomy 23:9-11 Strict rules for soldiers going to war. Anyone who became unclean due to some "occurrence in the night" had to stay outside of the camp until evening. God expected the army to be holy.
1 Samuel 21:4-5 David's men ate of the holy temple bread, but had to be ceremonially clean (specifically, had stayed away from women) to do so.

Menstruation

Genesis 31:34-35 Rachel used menstruation as a ruse to hide her father's stolen idols.
Leviticus 15:19-30,33 Laws of uncleanness (for tabernacle—v.31).
Leviticus 18:19; 20:18 Don't approach a woman to uncover her nakedness while she is in her customary impurity. What does this mean in light of Leviticus 15:24,33? That says whoever "lies with her at all" so maybe that means someone who shares a bed even without having sex.
Leviticus 12:1-8 Uncleanness due to childbirth, similar to menstruation. 33 days for a baby boy, 66 days for a baby girl. No explanation why it is double time for a female child.
Ezekiel 18:6; 22:10 God criticises Israel because among other sins, men approach/violate women who are set apart in their monthly impurity.
Ezekiel 36:17 Israel's sins compared to uncleanness of a woman in her customary impurity.

What is the meaning of these rules? Leviticus 17:11 Meaning of blood in relation to sacrifices.

Circumcision

Genesis 17:10-14,23-27 Covenant with Abraham.
Exodus 12:43-48 Circumcision is a prerequisite for keeping the Passover.
Leviticus 12:2-4 Circumcise a baby boy on the 8th day.
Joshua 5:2-9 Circumcision of Israel before entering the promised land.
Romans 2:25-29
1 Corinthians 7:17-20 Remain as you were when called, whether circ or uncirc. Circ is nothing; uncirc is nothing; keeping the commandments is what matters.
Galatians 5:6 In Christ Jesus neither circumcision nor uncircumcision avails anything, but faith working through love.
Philippians 3:3 Spiritual circumcision.
Colossians 2:11 In Christ we were circumcised with the circumcision made without hands.

Fertility

The Bible says fertility is a blessing. God has sometimes used barrenness as a curse or punishment from God. But barrenness has sometimes been not a curse, but simply a trial that couples have had to endure, and sometimes which God has miraculously healed.

Genesis 15:1-6; 16:1-5; 17:5-6,15-21; 18:9-15; 21:1-7 Abraham and Sarah.
Genesis 25:20-26 Isaac and Rebekah.
Genesis 29:31-35; 30:1-24 Jacob, Leah and Rachel.
Judges 13:1-5,24 Samson's parents, Manoah and unnamed.
1 Samuel 1:1-20 Samuel's mother Hannah.
Luke 1:5-25,57-58 John the Baptist's parents, Zacharias and Elizabeth.

Gender Differences

Genesis 17:10-14,23-27; Exodus 12:43-48; Leviticus 12:2-4; Joshua 5:2-9 Circumcision for males only.
Exodus 1:15-22 Pharaoh sought to kill off the male baby Israelites, to weaken their nation.
Exodus 22:16-17; Deuteronomy 22:28-29 Man who lies with a virgin not betrothed or married. He must marry her. It appears that the man is regarded as having greater culpability for extra-marital sex, and a higher expectation of owing financial duty to her. Perhaps also this shows the loss of virginity was a more profound loss for the woman than for the man.
Leviticus 12:1-8 Uncleanness due to childbirth, similar to menstruation. 33 days for a baby boy, 66 days for a baby girl. No explanation why it is double time for a female child.
Leviticus 27:1-7 Different monetary valuations of people dedicated to the Lord, depending on whether male or female.
Numbers 5:11-31 Ritual for wife suspected of adultery.
Numbers 31:17-18; Deuteronomy 21:10-14 When Israel went to war, they could take young women captive to be wives, but kill all the males, and kill the older, non-virgin women.
Deuteronomy 22:13-21 Blood on the wedding sheets as evidence of a woman's virginity. Death penalty for a woman who is not a virgin as expected. Described as "played the harlot".
Deuteronomy 22:23-27 Rape away from built-up areas. Asymmetry between rules for man and woman (it is presumed that the man is the perpetrator of rape on a woman victim).
God allowed polygamy, as a man marrying multiple wives, but never a woman marrying multiple husbands. This seems to be related to the symbolism of marriage representing the relationship between God/Jesus and God's people.