Q. In the Bible, sex before marriage is considered immoral. It’s called the sin of “fornication.” But the Bible gives no explanation (that I have seen) of why it’s wrong to have sex before marriage. In 1 Corinthians, for example, Paul calls those who do this “sexually immoral.” But why, why is it wrong? How could having sex, something that all married couples do regularly, be unclean and immoral before two people are married?
This is an excellent question, because we don’t usually consider the morality of an action to depend on its setting or context. If something is a good thing to do, such as telling the truth, it should be good for everyone, everywhere to do it. And if something is wrong, such as striking another person in anger and causing them bodily harm, then it should be wrong for everyone, in every context. Husbands and wives certainly don’t get an exemption that permits them to engage in domestic violence.
So why does the Bible allow and encourage sex within marriage but say it’s wrong outside of marriage? Why shouldn’t two people who love each other be able to express it in this way even if they aren’t married?
The Bible actually does give the reason why, in places like the book of Hebrews, where it says, “Let marriage be held in honor by all, and let the marriage bed be undefiled.” But in order to recognize the reason that’s being given here, we need to understand what the Bible means when it uses specific terminology like this.
In the first part of the Bible, in the law of Moses, things are generally considered “common” and “clean.” But if something is set apart for a special purpose, it becomes “holy” rather than “common.” And if a person or thing becomes exposed and vulnerable through some breach in its creaturely integrity, that person or thing becomes “unclean.”
“Unclean” doesn’t mean “dirty” or “bad.” It means that special care and protection is needed, usually involving temporary separation from the community until the breach is repaired. In the law of Moses things like a skin disease, which breached the integrity of the body’s outer layer, created this kind of ceremonial “uncleanness.” The example I like to use from modern life is a person who has lost their hair because of chemotherapy treatments. We usually allow and encourage such a person to stay home or wear a wig until their hair has grown back. We protect their dignity and preserve a proper sense of who they are by not making them engage others when most of their hair has visibly fallen out. (Alternatively, I’ve heard of friends and family shaving off their own hair as a gesture of solidarity and identification, so that the person will know that they are loved and unconditionally accepted. The family and friends are saying, “We know the real you and that’s not affected by superficial considerations.”)
There are two other important biblical terms for us to appreciate. To treat something holy as if it were common is to “profane” that holy thing. Jesus spoke of the way the priests “profaned” the sabbath (that is, they treated it as if it were an ordinary working day) because their shifts were scheduled on every day of the week. (In this case, maintaining continual worship took precedence over sabbath observance for priests whose shifts fell on that day; no individual priests worked seven days a week.)
And to treat something holy as if it were unclean is to “defile” that holy thing. This is a more serious matter, because in the Bible anything that is made holy—set apart for a special divine purpose—has to be uncompromised in its creaturely integrity.
And this is what the Bible is saying in the book of Hebrews about keeping sex within marriage so that it will be undefiled. It’s saying that God has made sex “holy,” that is, God has set sex apart for a special reason, and to that end God has limited sex to within marriage.
So what is that reason, and why the limitation?
Is it so that a desire for the pleasure of sex will serve as an incentive for people to commit to marriage? Well, the pleasure certainly isn’t a disincentive, but pleasure is not the ultimate purpose of sex, and so that’s not the reason why it’s limited to marriage.
Is it so that children who are conceived through sex will be raised in a stable home? This is another additional benefit of God’s plan, since marriage is meant to provide a stable, loving environment for children, but since procreation is not the ultimate purpose of sex, this is not the real reason, either.
The ultimate purpose of sex is intimacy. The Bible explains this at its very beginning, in the book of Genesis, when it says that “a man leaves his father and mother and is united to his wife, and they become one flesh.” It’s sometimes hard for us to appreciate today how revolutionary this statement was in its day. In ancient cultures (as in some modern ones) blood relations were supreme. Primary loyalty was owed to one’s family and clan of origin. When a man married, his wife was simply added to the clan as a junior member, and both had to be careful to obey his parents and the other senior members of the clan.
But God’s plan was that husband and wife would create a whole new family of their own, with their primary loyalty being to one another. They would be “one flesh”—they would belong to one another more than they belonged to their blood relatives. And this would be established, affirmed, and celebrated through the act of sex, in which the two, for a time, would literally join their bodies together. The Bible is describing this ideal situation of intimacy when it says that the first couple “were both naked, and they felt no shame.”
So sex was something that already existed (in the animal kingdom, for example), but among humans God made it holy, that is, God set it apart for a special purpose, as the joyful and triumphant expression of the new oneness between husband and wife.
So how does having sex outside of marriage make this holy thing “unclean,” that is, something that makes a person exposed and vulnerable? Since the ultimate purpose of sex is intimacy, when you make love with someone, you don’t just reveal your body to them. You inevitably expose your soul—your hopes, dreams, fears, your deepest and most powerful thoughts and emotions. And God wants this kind of exposure to happen within the protection of an unconditionally committed lifelong relationship, because only within the safety and security of such a relationship can two people help each other explore and work out all the powerful, complicated, and potentially beautiful things they have inside.
In other words, sex for people is actually something that is intrinsically holy. In other cases God chose things that could just as easily be common to serve holy purposes, and in those cases there could be exceptions to their exclusive use for holy purposes. Jesus cited the example of David and his men eating the bread that was reserved for the priests to justify his work of healing on the Sabbath. Bread is just bread, and Saturday is just Saturday, until God chooses to set them apart for other purposes, and sometimes even higher considerations can intervene.
But sex is never just sex. It always involves the exposure of heart, soul, and body to another person, and God means for that to happen in a context of safety, security, and lifetime commitment—within marriage. That’s why Paul says in another of his letters, 1 Thessalonians, that if we have sex with another person not in this “holy and honorable” way, but in the “passion of lust,” we sin against and defraud that other person. In other words, we take something from them that we’re not entitled to: we take their intimate self-disclosure without providing the security and protection they deserve and require.
These are the reasons that the Bible gives for why sex is to be reserved for marriage. Now I realize that someone who doesn’t believe in God or in the teachings of the Bible, at least to the extent of believing that God considers some things common and has set other things apart as holy, may not agree with these reasons. They may feel, in fact, that there are times when sex is just sex and they may believe that there’s nothing wrong with that. I can’t convince someone otherwise if they don’t share this biblical view of God’s creative purposes. But for those who do share it, I hope that I have been able to explain here why the Bible teaches what it does about God setting aside sex for a special purpose within marriage.