“Sex outside of marriage,” Woody Allen once said, “is a pretty empty experience. But as far as empty experiences go, it’s a pretty good one.” The famous comedian’s joke might be good for a chuckle but, in the end, his quip isn’t quite right. God designed sex for marriage and sex outside of marriage is indeed empty and in the end is not “pretty good” but “pretty bad” for us holistically.

That is the point of the seventh commandment, “You shall not commit adultery” (Ex 20:14). Adultery dishonors God by breaking the marriage covenant made in his presence, disrespecting and degrading one’s sexual partner, and corrupting his or her marriage. Adultery is the violation of a unique, God-designed relationship. When we commit adultery, therefore, we are violating a covenant we made with God.

Further, Jesus deepened and extended the seventh commandment, making clear that it carries implications far beyond the physical act of having sex with another person’s spouse. He says that a man sins if he even looks at a woman with sexual intent (Mt 5:17, 28). Indeed, the seventh commandment addresses the significance of sexuality and marriage and how married partners ought to live within the parameters of marriage.

When God created man and woman and he pronounced his creation “very good” (Gem 1:31). Their relationship with God and with each other was characterized by the same shalom that characterized the entire created order pre-Fall. However, after the Fall, their relationship with one another was disrupted. One aspect of the curse was that the man would rule over the woman, whereas initially they would rule together without man ruling over the woman (Gen 1:26-28). Through Christ’s redemption, this “rulership” is transformed into servant leadership and is characterized by the same type of tenderness as Christ exhibits toward the church (Eph 5:22-33).

When God created man and woman he did so by commanding them to “Be fruitful and multiply; fill the earth and subdue it” (Gen 1:28). The man was to “leave his father and mother and be joined to his wife, and they shall become one flesh” (Gen 2:24). This leaving and cleaving, in order to be fruitful and multiply, constitutes the institution of marriage.

To cleave to one’s wife is to join her physically and emotionally, to have a loving friendship and sexual relationship. “The ‘cleaving’ mentioned in Genesis 2 refers to an intense love that radiates in body and soul throughout all areas of fellowship.” Similarly, the biblical description of husband and wife as “one flesh” refers to the joining of the entire person to the other person, resulting in a comprehensive personal communion (Eph 5:22-33).

Thus, the seventh commandment speaks to trends in American society—trends toward viewing polyamory, polygamy, and open marriages as socially and morally acceptable. Polyamory (view my article here) refers to a situation in which people have multiple romantic relationships at the same time. Polygamy (view my article here) refers to the practice of having more than one husband or wife at the same time. Open marriage refers to a married couple’s agreement with one another that each is allowed to have sex outside of marriage. Each of these trends violates the seventh commandment.

This commandment has implications that reach even further than one might initially imagine. Consider, for example, artificial insemination. Yes, there are some types of artificial intervention—such as C-sections, elevation of a man’s sperm count, surgery on a woman’s ovaries, and artificial insemination using the husband’s sperm. However, the seventh commandment implies that it is immoral to use a sperm donor to artificially inseminate. To use sperm from a donor is to violate the marriage covenant by inviting a third party into marriage. In fact, we might even call this artificial adultery (along with other types of artificial adultery, such as sex robots or pornography).

Consider, similarly, the phenomenon of in vitro fertilization (IVF). In vitro fertilization is a type of artificial insemination in which the man’s sperm is made to fertilize the woman’s egg outside of the woman’s body. After fertilization has occurred, the embryo is planted in the woman’s uterus. One of the problems with this technology is that it opens the door for surrogate motherhood (in which a woman carries another couple’s child to birth even though it is not genetically connected to her). Thus, a morally acceptable IVF is on in which the embryo originates with the married couple and is not discarded or sold.

Additionally, the seventh commandment speaks against practices such as pedophilia and incest. Pedophilia, the act of sex between adults and children, is prohibited just like any other sex outside of the act of marriage. But unlike other sinful sexual acts, it is deeply and often irreparably harmful to the child. Jesus warned against corrupting a child; he explained that adults who violate a child will have to deal with Jesus himself (Mt 18:5; Mk 9:37) and would rather have a millstone tied around their neck and be drowned in the ocean (Mt 18: 6). Similarly, incest, which is the abuse of a child within the home by an adult family member. As with pedophilia in general, the biblical teaching sternly prohibits incest as sinful, deeply damaging to the child, and subject to harsh consequences from the Divine Lawgiver.

In summary, God’s design for human flourishing paces sexual activity firmly within the bounds of marriage. Marriage is a one-flesh union—between one man and one woman—that is oriented toward procreation. And it is God’s provision for sexual fulfillment. During this era of American history, the seventh commandment seems backwards and oppressive. Yet, God’s law is timeless, applicable to all people or all times and all places. In order to be on the “right side of history,” therefore, we must place our lives in conformity with God’s law for marriage and sex.


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