What does the Bible say about sex before marriage?
The Bible has no separate category for "sex before marriage" — it files it under one word, and then tells you what to do about it. The passages the commentators return to are 1 Corinthians 6, Hebrews 13:4, 1 Thessalonians 4 and 1 Corinthians 7, and together they raise two questions: why is this sin treated so seriously, and what does God provide instead?
The word covers more than most people think
Older translations use "fornication" where the ESV says "sexual immorality," and one writer spells out exactly how wide that term runs — including the case of a couple who fully intend to marry.
Arend RemmersHoly Scripture not only calls prostitution fornication, but all extramarital intercourse, even where there may be the intention to get married, and even if it is done only once (compare Genesis 34 and 38). In the world today the word fornication is only used in connection with the first meaning. In the New Testament, however, extramarital intercourse in general is called fornication, that of married persons is called adultery, and both are condemned as abominable sin (Matthew 15:19; 1 Corinthians 6:9; Hebrews 13:4).
The same writer notes that Paul told the Ephesians such things must not even be named among God's people — meaning we should not mention them lightly and so make little of them.
Why the body is the issue
Paul's argument in 1 Corinthians 6 is not first about rules but about ownership. The Corinthians lived in a city where this was normal, and Paul answers with the believer's union with Christ.
J. N. DarbyBut the doctrine that the body is for Christ decided another question, to which the depraved habits of the Corinthians gave rise. All fornication is forbidden. To us, with our present Christian habits of mind, it is a thing of course — to pagans, new; but the doctrine lifts every subject. Our bodies are the members of Christ. Another truth connected with this is of great importance: if by union according to the flesh two were one body, he who is united to the Lord is one spirit.
That union raises the cost of the sin, because it is committed by something already bought and already occupied.
William KellyHow dreadful then to think not merely of the body so misused, but the Christian's body, temple of the Holy Spirit as it is! not from any mere setting apart to Him, but from His being in us, and this from God, on the ground of purchase by Christ's blood. Therefore the apostle appeals to them to glorify God in their body.
Flee — not fight
The command in verse 18 is unusual. Other sins are met with resistance; this one is met with distance.
Leslie M. Grant"Flee from sexual immorality." In this one is not told to fight, but to keep far from it, as Joseph fled from the wife of Potiphar. Other sins may not involve the body in this way, but this is sin against one's own body.
Another writer draws the practical edge from the same verse: Paul gives no room for any flirting with evil, and Scripture commands us to put a great distance between ourselves and the temptation, since obedience to God's Word is the escape He has provided.
What God provides instead
Scripture does not answer desire with mere suppression. Hebrews 13:4 is read by one commentator as a command rather than a statement, and he is careful about what it does not cover.
William KellyMarriage is only honourable where God's will is observed. Hebrews 13:4 in no way sanctions or makes holy a forbidden union. The true rendering is, Let marriage be honourable — not "among all," but "in all things" — and the bed undefiled… It is an instruction, not a statement of fact.
Paul also treats marriage as a real relief for those who cannot live single, though commentators note he gives this as permission rather than command.
A. PridhamBut if they cannot contain themselves, let them marry… Godliness with contentment is great gain; without it godliness itself is endangered. A man must be his own judge in this matter. Marriage is honourable if he chooses it.
Engagement is not a licence
One writer applies all this directly to couples who have already promised themselves to each other.
Brian WarnesIt is normal for there to be a display of affection between two who have committed themselves to each other; yet there is need for self-control and restraint… We must leave until marriage that freedom to enjoy all the privileges of physical closeness and union; we are forbidden to have intercourse outside of marriage and must not allow our physical emotions to control us. Such actions as staying unaccompanied in the same house should be avoided, as they could lead to temptation and suspicion.
He treats cohabitation as clearly fornication, since there is no commitment to marry and no public declaration of marriage.
For those who have already failed
Paul's list of sins in 1 Corinthians 6 does not end in condemnation.
F. B. HoleOf all the Christians of the apostolic age that we know anything about, they stand out as the least marked by practical holiness. Their behaviour was open to much criticism, and they got it from the Apostle Paul in very plain language… Later in the same letter, after mentioning many of the terrible things that filled the heathen world, he said, "And such were some of you: but… you were sanctified."
Summary
- Named — Scripture calls all sex outside marriage fornication, including between a couple who intend to marry, and including once.
- Owned — the reason is union: the believer's body is a member of Christ and the temple of the Holy Spirit, bought at a price.
- Fled — the command is not to resist but to withdraw, keeping distance as Joseph did.
- Provided — God's answer to desire is marriage, to be held honourable in all things, not a forbidden union blessed after the fact.
- Restored — Paul's own words to a failing church were "such were some of you… you were sanctified."