Why Is Sex Reserved for Marriage?

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Nathan Pickup

In my last article, I attempted to explore the theology behind God’s invention of sex within his “good” creation (Gen. 1:31). But even if we understand the theological purpose of sex, we may still wonder why God demands that sex be exclusive to married couples. In my experience, Christians spend a lot of time promoting the restriction of sex to the marriage bed (Heb. 13:4), but much less time explaining the purpose of that restriction. If we fail to address the purpose of God’s restriction on sex, then we risk making the restriction appear arbitrary. After all, can’t the transcendent oneness that sex achieves be accomplished outside of marriage? Why must I be married to someone to achieve oneness with that person? 

We will never understand God’s restriction on sex if we fail to appreciate our created purpose of reflecting the Creator. We are made in the image of Yahweh himself, and are thus created to reflect his nature in our God-given dominion over his creation (Gen. 1:26-31). If we claim to be God’s people, then we’re accepting the validity of this created purpose for mankind. This allows us to see greater truths in marriage and sexuality than the world, which has ousted divine significance from “earthly” events. In my first article in this series, I discussed the theological significance of marriage, and how it was created for the purpose of dealing with mankind’s loneliness by mirroring the covenant relationship between Christ and his church (Eph. 5:25-33). This leads to a better understanding of sexuality, which was created to attain and express the oneness that the covenant of marriage achieves. By creating marriage and sexuality, God has built into creation physical copies of heavenly things. But Satan offers sexuality apart from these things, and in doing so he destroys the theological truths that sexuality was designed to espouse.   

Sex outside of marriage destroys the idea of covenant oneness. Sex is the incarnation of the spiritual oneness that occurs through the covenant of marriage. Extramarital sex seeks oneness with someone with whom we have no covenant relationship. It is often driven more by lust than seeking oneness, and therefore becomes more about us instead of pointing to something greater than us. And even when people in a committed but non-marital relationship give themselves sexually to each other, it’s still done without the partners having pledged themselves to the idea of covenant. Thus, it is seeking oneness without having fully given one’s self to a lifelong covenant with another. This type of intimacy in no way reflects God’s relationship with his people. God has only sought oneness with humanity through a covenant relationship; he does not seek oneness and intimacy with anyone other than his covenant people, to whom he pledged himself indefinitely. Marriage and sex were designed to model that same fidelity. If God’s joy in achieving oneness with his people only occurs through a covenant relationship, then our participation in marriage and sexuality should mirror that fact, if we indeed care about reflecting God’s image. God’s restriction of sex to the marriage bed is his preservation of this creation’s physical picture of the oneness achieved through transcendent covenant love—a love devoted to something greater than the individual partners who pledged themselves to it.

Another reason extramarital sex is divinely forbidden is because it produces human life outside the bounds of covenant love. God’s design was that human life would be created, and then nurtured and raised, within a covenant relationship between two different but complementary beings in God’s image. This design parallels the experience of those who have been “born again” into God’s covenant community, and have then been nurtured and raised within that covenant environment. This is not an accidental parallel—God purposefully built into creation physical elements that would demonstrate heavenly realities. God wanted human beings to create and raise life within covenant love, thus demonstrating and experiencing his covenant character and the life that it brings to all of his people. But extramarital sex ruins this ideal by creating life outside of covenant devotion, and often results in raising that new life without a model of covenant relationship. Even worse, our culture has amputated sex from the idea of covenant and thus views sexually produced life as unwanted, leading to the heinous act of abortion—killing human life made in the image of God. By restricting sex to the marriage bed, God is preserving this creation’s physical picture of the spiritual life covenant love has produced for all of mankind who would accept God’s covenant offer.

Sex is not merely an expression of love, it’s an expression of covenant. Amputating sex from covenant is man’s attempt to separate what God has joined together. Sex outside the covenant of marriage destroys our created purpose of reflecting God’s covenant character, and disfigures the spiritual aspects of covenant oneness that marriage and sexuality were designed to reflect. The choice to follow God is not the choice to follow divine arbitrary restrictions; it’s the choice to see creation as God designed it and to live within that design, in the conviction that God’s design is better than anything Satan has to offer. Therefore, all of our actions should seek to imitate God’s covenant nature. This goal and commitment should help us better understand why God created sex exclusively for partners within the covenant relationship of marriage.