Sexual Immorality in the Bible: Meaning, What It Covers and Forgiveness

In the Bible, sexual immorality means sexual relations outside the marriage of a man and a woman. The New Testament word is porneia, which the King James Version translates “fornication,” and it covers adultery, sex before marriage, incest and prostitution. Sex within marriage is not immoral, and the letters that warn against porneia also promise forgiveness for it.

What does the word porneia mean?

Porneia comes from pornē, the Greek word for a prostitute. Thayer’s Greek lexicon traces pornē to a verb meaning “to sell” and defines her as “a woman who sells her body for sexual uses.” By the time the New Testament was written, porneia had grown much wider than paid sex. Thayer gives its plain meaning as “illicit sexual intercourse in general,” and Strong’s concordance glosses it “harlotry (including adultery and incest).” The noun occurs about 25 times in the New Testament, with one more in the Greek text behind the King James Version, at Romans 1:29.

Older English Bibles render it “fornication”; modern ones say “immorality,” “sexual immorality” or “unchastity.” Fornication in its narrow sense means sex between two people who are not married. The Catechism of the Catholic Church defines it as “carnal union between an unmarried man and an unmarried woman.” Scripture uses the word in both senses. Sometimes it names every unlawful union, and sometimes it stands beside adultery as a separate sin, as in Jesus’ list of what comes out of the heart: “evil thoughts, murders, adulteries, fornications, thefts” (Matthew 15:19).

Scripture also uses the word as a picture of unfaithfulness to God. The prophets spoke of idolatry as prostitution. Revelation describes “the great whore,” “with whom the kings of the earth have committed fornication” (Revelation 17:1–2), and says that she “is that great city, which reigneth over the kings of the earth” (Revelation 17:18). There the word means idolatry rather than a sexual act.

One common claim about the word is wrong. The English word “pornography” does not come from porneia. Both come from pornē. “Pornography” was formed from the Greek pornographos, “(one) depicting prostitutes,” from pornē and graphein, “to write,” and it entered English in 1842 to describe obscene paintings from the ancient world.

Which acts does the Bible count as sexual immorality?

Scripture does not give one master list. The Law of Moses names forbidden unions in Leviticus 18 and 20, and the apostles’ letters name sexual sins among other sins. Paul’s list in Galatians opens with them: “Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness” (Galatians 5:19). Put together, the passages cover these acts.

Two words in 1 Corinthians 6:9 are hard to translate. The King James Version renders them “effeminate” and “abusers of themselves with mankind”; the Catholic New American Bible renders them “boy prostitutes” and “sodomites,” and its note explains that the first word “may refer to catamites, i.e., boys or young men who were kept for purposes of prostitution.” Translations differ over how widely the two words reach.

Paul gives the reason all these acts belong together: “Now the body is not for fornication, but for the Lord; and the Lord for the body” (1 Corinthians 6:13). A few verses later he tells the church at Corinth, “Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body. What? know ye not that your body is the temple of the Holy Ghost which is in you?” (1 Corinthians 6:18–19). The New American Bible’s note says the phrase “against his own body” expresses “the intimacy and depth of sexual disorder.” To the Thessalonians he calls avoiding it part of becoming holy: “For this is the will of God, even your sanctification, that ye should abstain from fornication” (1 Thessalonians 4:3). The common question of sex before marriage has its own page.

Is sex itself a sin?

No. Scripture treats sex within marriage as God’s gift. Genesis describes marriage as a union of bodies from the start: “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). One of the Bible’s words for sex is “knew”: “And Adam knew Eve his wife; and she conceived” (Genesis 4:1).

Proverbs tells a husband to “rejoice with the wife of thy youth” (Proverbs 5:18). The Song of Solomon is a whole book of love poetry between a bride and her beloved: “My beloved is mine, and I am his” (Song of Solomon 2:16). Hebrews honours marriage and warns against sex outside it in the same verse: “Marriage is honourable in all, and the bed undefiled: but whoremongers and adulterers God will judge” (Hebrews 13:4).

Paul even tells married couples not to refuse each other. “Let the husband render unto the wife due benevolence: and likewise also the wife unto the husband” (1 Corinthians 7:3). “Due benevolence” means what each owes the other in marriage. A couple may abstain for a season of prayer, but only by agreement and only for a while: “Defraud ye not one the other, except it be with consent for a time, that ye may give yourselves to fasting and prayer; and come together again” (1 Corinthians 7:5). The Bible never asks married people to live without sex as a rule. Most of its limits concern partners, not what a husband and wife do together, and it gives them no list of forbidden positions. The Law of Moses did set one limit within marriage: “thou shalt not approach unto a woman to uncover her nakedness, as long as she is put apart for her uncleanness,” that is, during her monthly period (Leviticus 18:19; 20:18). Churches also differ over other limits; the Catholic Church, for example, teaches that contraception within marriage is wrong.

The churches set out their teaching in their own documents. All four below place sex within marriage.

Are lustful thoughts and pornography sexual immorality?

Jesus applied the commandment against adultery to the heart as well as to the act: “Ye have heard that it was said by them of old time, Thou shalt not commit adultery: But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart” (Matthew 5:27–28). His words concern looking in order to lust, not noticing that someone is attractive. The Didache, an early Christian teaching manual also called the Teaching of the Twelve Apostles, puts the same warning as advice to a young believer: “My child, be not a lustful one; for lust leads the way to fornication.”

Pornography falls under that warning. The Catholic Catechism says it “offends against chastity because it perverts the conjugal act, the intimate giving of spouses to each other.” The practical side of the struggle, how to overcome lust and how to stop watching porn, has its own pages.

What was the punishment for sexual immorality in the Bible?

The Law of Moses set severe penalties for Israel’s courts, death among them. Most of them appear in Leviticus 20 and Deuteronomy 22.

The town law assumed that a woman who cried out in a town would be heard and helped. The verses that follow it treat a woman forced where no one could hear her as innocent, and the guilt as the attacker’s alone; the section on abuse below returns to them.

Jewish courts later surrounded these penalties with demanding rules of evidence. The Mishnah, the early collection of rabbinic law, records this saying: “A Sanhedrin that executes a transgressor once in seven years is characterized as a destructive tribunal.” It adds that Rabbi Tarfon and Rabbi Akiva said that had they sat on the court, “no person would have ever been executed,” though Rabban Shimon ben Gamliel disagreed with them.

The New Testament gives the church no such penalties. When a man at Corinth had his father’s wife, Paul told the church to remove him from its fellowship: “put away from among yourselves that wicked person” (1 Corinthians 5:13). The final warning is about God’s kingdom, not a human court. After his list in Galatians Paul writes, “they which do such things shall not inherit the kingdom of God” (Galatians 5:21).

The Gospel of John tells how the law’s penalty was once brought to Jesus. Scribes and Pharisees set before him “a woman taken in adultery” and reminded him that “Moses in the law commanded us, that such should be stoned.” He answered, “He that is without sin among you, let him first cast a stone at her.” When her accusers had gone he asked, “hath no man condemned thee?” She said, “No man, Lord,” and he told her, “Neither do I condemn thee: go, and sin no more” (John 8:3–11). The New American Bible’s note says the story is “missing from all early Greek manuscripts” of John, and adds: “The Catholic Church accepts this passage as canonical scripture.”

Is a victim of sexual abuse guilty of sexual immorality?

No. Abuse is a sin committed against the victim, not by the victim. The Law of Moses draws this line itself. When a man forced a betrothed woman in the open country, “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: for as when a man riseth against his neighbour, and slayeth him, even so is this matter” (Deuteronomy 22:25–26). The law compares her to the victim of an assault, and the guilt is the attacker’s.

Second Samuel tells of Tamar, the sister of Absalom, who begged Amnon, another son of David, “Nay, my brother, do not force me,” and asked him, “whither shall I cause my shame to go?” Scripture puts the blame on him: “he would not hearken unto her voice” (2 Samuel 13:12–14). The Catholic Catechism calls rape “the forcible violation of the sexual intimacy of another person” and says, “It causes grave damage that can mark the victim for life.” It adds, “Graver still is the rape of children committed by parents (incest) or those responsible for the education of the children entrusted to them.” A child who is abused has done nothing wrong.

Anyone carrying this kind of shame carries a weight that belongs to someone else. Telling a trusted adult, a doctor, a counsellor or the police is a right step, and so is bringing the grief to God, who in the law counted the woman in the field as the one wronged.

Can God forgive sexual sin?

Yes. Right after the list of sins in 1 Corinthians that begins with “fornicators” and ends with “extortioners,” Paul writes to real people in a real church: “And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God” (1 Corinthians 6:11). Some of the first Christians had lived the way the list describes.

King David took Bathsheba, another man’s wife, and then wrote the order that put her husband Uriah “in the forefront of the hottest battle” (2 Samuel 11:4, 15). When the prophet Nathan confronted him, “David said unto Nathan, I have sinned against the Lord. And Nathan said unto David, The Lord also hath put away thy sin” (2 Samuel 12:13). Psalm 51, a prayer of repentance, asks, “Wash me throughly from mine iniquity, and cleanse me from my sin,” and “Create in me a clean heart, O God; and renew a right spirit within me” (Psalm 51:2, 10).

The promise is the same for every sin: “If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness” (1 John 1:9). Jesus’ words to the woman in John 8 hold both halves together. He did not condemn her, and he sent her out to live differently: “go, and sin no more.”

Related reading

• 23 Bible verses about sexual immorality
• What sex acts does the Bible forbid?
• Is kissing before marriage a sin?
• Bible verses about being forgiven
• Bible verses about shame
• Prayers after sinning: confession, forgiveness and strength