Religion in the United States
What scripture, churches and faith communities teach about sex outside marriage, and how that teaching has changed.
All topics · 10
Fornication in the Bible: Key Verses from the King James Version
The King James Bible uses “fornication” 26 times to translate the Greek porneia, a broad term for illicit sexual relations. Paul tells readers to “flee fornication” (1 Corinthians 6:18), lists it among the works of the flesh (Galatians 5:19) and presents marriage as a safeguard (1 Corinthians 7:2). Churches differ on how widely the word applies.
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Sex Before Marriage and Sin: How Christian Denominations Differ
Catholic, Latter-day Saint and evangelical churches teach that sex belongs only within marriage, while some mainline Protestant bodies now use more open wording. Believers are more divided than their churches: in Pew’s October 2019 survey, 57% of U.S. Christians said sex between unmarried adults in a committed relationship is sometimes or always acceptable.
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What the Catholic Catechism Says About Fornication
The Catechism of the Catholic Church defines fornication as carnal union between an unmarried man and an unmarried woman (paragraph 2353). It calls it gravely contrary to the dignity of persons and of human sexuality, and treats it under the sixth commandment, which Church tradition reads as covering the whole of human sexuality.
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The Latter-day Saint Law of Chastity Explained
The law of chastity is a commandment of The Church of Jesus Christ of Latter-day Saints: no sexual relations outside a legal marriage between a man and a woman. Members who commit serious sexual sins are asked to confess to a bishop or stake president. Church schools such as BYU write the same standard into their Honor Code.
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How American Evangelicals View Sex Before Marriage
Evangelical churches generally teach that sex is reserved for marriage, a message popularized from the 1990s by pledge campaigns such as True Love Waits. Evangelicals were the most conservative major Christian group in Pew’s 2019 survey: 46% said sex in a committed unmarried relationship is sometimes or always acceptable, versus 67% of mainline Protestants.
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Living Together Before Marriage: What Christian Teaching Says
Many churches treat cohabitation as "living in sin" when it involves a sexual relationship, citing passages such as 1 Corinthians 7:2. American believers disagree: Pew found in 2019 that 74% of Catholics accept unmarried couples living together even if they do not plan to marry, compared with 47% of Black Protestants and 35% of white evangelicals.
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"Flee Fornication": Reading 1 Corinthians 6:18 in Context
"Flee fornication" is the King James wording of 1 Corinthians 6:18, where Paul tells the church at Corinth to run from porneia and argues that this sin, unlike others, is committed against one's own body. The NIV renders it "flee from sexual immorality." The next verse calls the body a temple of the Holy Ghost.
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What Hebrews 13:4 Says About Marriage, Whoremongers and Adulterers
Hebrews 13:4 states in the King James Version that marriage is honourable and the marriage bed undefiled, and warns that God will judge "whoremongers and adulterers." The Greek word behind "whoremongers," pornos, is also translated "fornicator" elsewhere in the KJV. Christians often cite the verse to argue that sex belongs within marriage.
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Fornication and the Ten Commandments: What "Thou Shalt Not Commit Adultery" Covers
Not by name. The Ten Commandments say "Thou shalt not commit adultery" (Exodus 20:14), which in biblical law meant intercourse involving a married woman. Many churches read it more broadly: Catholic tradition, which counts it as the sixth commandment, says it covers the whole of human sexuality, and Presbyterian catechisms list fornication under the seventh.
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"Saving for the Cause of Fornication": Understanding Matthew 5:32
In Matthew 5:32 Jesus says that a man who divorces his wife causes her to commit adultery, "saving for the cause of fornication." The Greek word is porneia. Readings divide: many Protestant churches see this exception clause as permitting divorce after sexual unfaithfulness, while churches that hold marriage indissoluble, including the Catholic Church, read it far more narrowly.
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