Deuteronomy 5:18

"You shall not commit adultery."

As we continue our study of the Ten Commandments as covered in the Heidelberg Catechism, we should realize that some of these commandments go against the grain of our culture more than others. This is particularly true of the seventh commandment, which prohibits adultery (Deut. 5:18). Of course, it is not that our society, in general, approves of extramarital affairs, although some people do argue in favor of such trysts. What we are saying is that when we consider the full scope of the seventh commandment, we find Western society increasingly resistant to the idea that there should be any limitations on sexual activity. Question and answer 108 of the catechism introduce its discussion of the seventh commandment.

Adultery is a particularly serious transgression of God's law for two main reasons. First, it is a violation of the earliest covenant that the Lord put in place between human beings. In the beginning, our Creator ordained that the proper place of sex is in the marriage covenant. It is an especially clear picture of the one-flesh nature of marriage and a source of great joy, not shame, in the context of a loving marital relationship between one man and one woman (Gen. 2:24–25). Adultery is a rejection of this great truth and, ultimately, a rejection of divine authority. The adulterous husband or wife spits in the face of God, essentially telling Him that He has no right to order the basic covenant upon which human society is based. If He has no authority in this relationship, as adulterers demonstrate by their behavior, then He has no sovereignty over human affairs at all. Thus, adultery is a blasphemous affront to God and His glory.

The blasphemous nature of adultery is also seen when we consider how the Bible speaks of marriage theologically. Throughout Scripture, the relationship between God and His people is likened to the relationship between a bride and her bridegroom (Isa. 61:10), and the worship of false gods is likened to adultery (Ezek. 16). Ultimately, adultery is a form of idolatry, a refusal to acknowledge God as the covenant Lord through the substitution of illicit sexual pleasure as a deity in His place. It is a violation of our relationship with Christ, who takes His church as His bride and proves to be the Husband who is never unfaithful (Eph. 5:22–33).

Coram Deo

Just as idolatry led to destructive consequences for the ancient Israelites, the analogous sin of adultery leads to destruction on an earthly level (2 Kings 17:6–23; Matt. 19:1–12). This should be enough to cause us to flee adultery, but knowing that this sin is an affront to God’s sovereignty is yet one more reason to maintain our chastity. Let us guard our hearts and seek intimacy with our spouses, that we might not succumb to the temptation of adultery.

For Further Study