We are studying the second half of the Ten Commandments, that portion of these statutes that deals most specifically with the relationships God intends human beings to have with one another, not least in the church. Exodus 20:14 gives us the seventh commandment: “You shall not commit adultery.”
The command to refrain from adulterous relationships is foundational to the well ordering of the marriage bond and the promotion of intimacy between husband and wife. As anyone who has seen or been affected by adultery knows, intimacy between married people who are not married to one another is profoundly destructive to the marriage, in many cases dealing irreparable harm to the relationship. Jesus permits (but does not command) divorce in the case of adultery, apparently because of the trust that is broken when an extramarital sexual encounter occurs and to protect the offended spouse from further damage (Matt. 5:31–32; 19:3–9).
Yet the seventh commandment prohibits more than just physical sexual contact between two people who are not married. As the Westminster Shorter Catechism explains, the law against adultery also forbids “all unchaste thoughts, words, and actions” (Q. 72). Indeed, Jesus tells us as much in the Sermon on the Mount (5:27–32). Besides adultery, then, the seventh commandment outlaws incest, sexual abuse, homosexuality, bestiality, pornography, and simply lust in general. It is a far-reaching law that we all broke the first time lust was aroused within us.
Note, however, that while all of these sins and many others are included under the broad scope of the seventh commandment, not all of them are equal in the harm they cause. Some of them cause more collateral damage to those not directly affected by the sin than others, and professing Christians who fall into these transgressions are to be disciplined with wisdom by the elders of the church and, if necessary, the secular authorities. Moreover, we must also realize that none of the sexual sins are unforgiveable, provided there is repentance and a good-faith effort to heal the damage when these sins are acted out (1 John 1:8–10). May we all treat repentant sexual sinners as we would any other transgressors — with love and compassion, not as pariahs.