What Sex Acts Does the Bible Forbid? The Full List

The Bible forbids sex outside marriage, both adultery and fornication. Leviticus 18 and 20 also forbid incest, sex during a woman’s period, sex between two men and sex with an animal, and other laws forbid prostitution and rape. Jesus goes further and adds lust in the heart. Between husband and wife, Scripture names no forbidden act, and the churches answer that question differently.

The longest list is in Leviticus 18, and it has a refrain. Six times in thirty verses God says, “I am the LORD” (Leviticus 18:2, 4, 5, 6, 21, 30). So before the list is about anything else, it is about whom we belong to: our bodies are not ours to give wherever we like, because we are his. Paul says the same to Christians in Corinth: “ye are not your own” (1 Corinthians 6:19).

What Scripture forbids	Old Testament	New Testament
Adultery	Exodus 20:14; Leviticus 20:10	Matthew 5:27–28; Hebrews 13:4
Fornication: sex between unmarried people	Exodus 22:16–17; Deuteronomy 22:20–21	Acts 15:29; 1 Corinthians 6:18; 1 Thessalonians 4:3
Incest	Leviticus 18:6–18; 20:11–21	1 Corinthians 5:1
Sex during menstruation	Leviticus 18:19; 20:18	Not named
Same-sex intercourse	Leviticus 18:22; 20:13	Romans 1:26–27; 1 Corinthians 6:9
Sex with an animal	Exodus 22:19; Leviticus 18:23	Not named
Prostitution	Deuteronomy 23:17	1 Corinthians 6:15–16
Rape	Deuteronomy 22:25–27	Not named
Lust in the heart	Exodus 20:17	Matthew 5:28

It says no to it from the very beginning: “Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh” (Genesis 2:24). Everything else in the list is there to guard that one flesh. Adultery breaks into a marriage that already exists, and the commandment against it is short, “Thou shalt not commit adultery” (Exodus 20:14), while Leviticus names both people, “the adulterer and the adulteress” (Leviticus 20:10).

The New Testament’s word for sexual sin is porneia, usually translated “fornication”. Thayer’s Greek lexicon defines it as “illicit sexual intercourse in general”. When the apostles met in Jerusalem over whether Gentile believers must be circumcised and “keep the law of Moses” (Acts 15:5), they laid on them “no greater burden than these necessary things”, and fornication was one of the four (Acts 15:28–29). Paul writes, “For this is the will of God, even your sanctification, that ye should abstain from fornication” (1 Thessalonians 4:3). There is more on this in what the Bible says about sex before marriage.

Leviticus 18 opens with a warning against “the doings of the land of Egypt” and “the doings of the land of Canaan” (Leviticus 18:3), and then lists what Israel must not do. Thirteen verses, 6 to 18, forbid sex with close family: a parent, a stepmother, a sister or half-sister, a grandchild, an aunt, a daughter-in-law, a brother’s wife, a woman and her daughter, or two sisters as wives. Then come four more: “thou shalt not approach unto a woman to uncover her nakedness, as long as she is put apart for her uncleanness” (18:19), “thou shalt not lie carnally with thy neighbour’s wife” (18:20), “Thou shalt not lie with mankind, as with womankind” (18:22), and sex with an animal, by a man or a woman (18:23). Verse 21, about offering children to Molech, sits among them and is not about sex.

The chapter binds foreigners living in Israel too, “any stranger that sojourneth among you” (18:26), and says the nations before Israel were judged for these same things (18:24). Leviticus 20 repeats most of them with their penalties. No Christian church applies those penalties today. The question we ask is which of the prohibitions still bind us, and the New Testament answers most of it.

Most of them we do keep, because the New Testament repeats them. Paul rebukes the church at Corinth for tolerating a man who “should have his father’s wife” (1 Corinthians 5:1). Romans 1 speaks of “men with men working that which is unseemly” (Romans 1:27). Adultery and fornication run through every list of sins Jesus and the apostles give: “For from within, out of the heart of men, proceed evil thoughts, adulteries, fornications, murders” (Mark 7:21).

The law against sex during menstruation is the one the New Testament never repeats, and here Christians differ. Leviticus 15:24 treats it as ritual uncleanness, lasting seven days, while 18:19 and 20:18 forbid it outright. John Piper of Desiring God concludes that “the prohibitions of sexual relations during menstruation … are not demanded of us as Christians”, and that a couple who disagree should settle it by love. Some Christian teachers still read Leviticus 18:19 as binding. Vasile Filat, writing for Moldova Creștină, a Christian media ministry in Moldova, answers the same question this way: “Sexual relations between spouses during the menstrual cycle of the woman are not permissible.”

Leviticus forbids a man to “lie with mankind, as with womankind” (18:22), and Paul names same-sex acts in Romans 1:26–27 and among the sins in 1 Corinthians 6:9. The Catholic Church teaches from these passages that such acts are sins. Its Catechism calls them “intrinsically disordered” (paragraph 2357), and in the next paragraph says that people with same-sex attraction “must be accepted with respect, compassion, and sensitivity” (paragraph 2358). Many Protestant teachers agree; John Piper argues that the prohibition is “rooted in nature”, so it did not end with the law of Moses.

Some Protestant churches now teach otherwise, the Episcopal Church in the United States among them. In 2015 its General Convention removed from its canons the wording that defined marriage as between a man and a woman, and authorized marriage rites for same-sex couples. The question is taken up in full in is homosexuality considered a sin?

It does, and the law of Deuteronomy takes care to say who is guilty. When a man forces a betrothed young woman in the field, “the man only that lay with her shall die. But unto the damsel thou shalt do nothing; there is in the damsel no sin worthy of death” (Deuteronomy 22:25–26). It compares rape to murder: “as when a man riseth against his neighbour, and slayeth him, even so is this matter”. When King David’s son Amnon attacked his half-sister Tamar, she pleaded, “Nay, my brother, do not force me; for no such thing ought to be done in Israel” (2 Samuel 13:12). Scripture records her plea and lays the deed on him alone: “being stronger than she, forced her” (2 Samuel 13:14).

Another law, harder for us to read, says that when a man seized a virgin who was not betrothed, he had to pay her father fifty shekels of silver and marry her, and “he may not put her away all his days” (Deuteronomy 22:28–29). The parallel law in Exodus let her father “utterly refuse to give her unto him”, and the man paid all the same (Exodus 22:16–17). Those laws bound the man to the woman for life, and they never blamed her.

The Catechism calls rape “always an intrinsically evil act” that “can mark the victim for life” (paragraph 2356). If this has been done to you, the sin was not yours. Please tell someone you trust, and if you are in danger now, call your local emergency number.

The Bible does not name it, but Jesus’ words reach it all the same: “Whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matthew 5:28). The tenth commandment had already said, “thou shalt not covet thy neighbour’s wife” (Exodus 20:17). The Catechism says pornography takes sexual acts “from the intimacy of the partners” to “display them deliberately to third parties”, and calls it “a grave offense” (paragraph 2354).

Scripture names none, apart from the law on menstruation, and it speaks warmly of what a married couple share. “Marriage is honourable in all, and the bed undefiled” (Hebrews 13:4). Paul gives husband and wife to each other: “The wife hath not power of her own body, but the husband: and likewise also the husband hath not power of his own body, but the wife.” Even their times apart are to be “with consent” (1 Corinthians 7:4–5). From Paul’s words two limits follow: nothing is forced on either spouse, and no one else is brought into the marriage bed, in person or on a screen.

On everything beyond that, the churches give different answers. Catholic teaching calls married love “noble and honorable” and says “the spouses do nothing evil in seeking this pleasure and enjoyment” (Catechism 2362). It also teaches that “each and every marriage act must remain open ‘per se’ to the transmission of life” (2366). So the Catholic Church forbids contraception, though it allows natural family planning based on “the use of infertile periods” (2370). The Anglican bishops at the Lambeth Conference of 1930 took a different view. For a couple with “a clearly felt moral obligation to limit or avoid parenthood” and “a morally sound reason for avoiding complete abstinence”, they agreed that “other methods may be used”. But the same conference condemned birth control chosen “from motives of selfishness, luxury, or mere convenience.”

Christians also ask about oral sex, and before marriage Catholic, Orthodox and evangelical teaching all treat it as sexual sin. Within marriage, Focus on the Family, an evangelical ministry, says “couples must use their own judgment”; Catholic writers allow it only as part of an act completed in intercourse, never in place of it; Orthodox answers vary.

Leviticus 18 answers with its own refrain, for every rule in it is set inside “I am the LORD your God”. The God who forbids is the God who made us for one another and gave sex its home in marriage, and he will not let it be used against the people he loves: a child in the family, a neighbour’s wife, a woman who cried and “there was none to save her” (Deuteronomy 22:27).

Paul gives the same reason with the cross in it. “Know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own? For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s” (1 Corinthians 6:19–20).

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