Heidelbasics: Brief Weekly Reflections on the Heidelberg Catechism by Rev. David Fagrey, Pastor of Grace Reformed Church of Rapid City, SD
108. What does the seventh commandment teach us?
That all unchastity is accursed of God, and that we should therefore loathe it with our whole heart, and live chastely and modestly, whether in holy wedlock or in single life.
The Seventh Commandment, “You shall not commit adultery,” forbids more than merely the outward act of adultery (sexual intercourse between a married person and a person who is not his or her spouse). Jesus said, “Whoever looks at a woman to lust for her has already committed adultery with her in his heart” (Matt. 5:28). Adultery begins with lust in our heart. “And pornography isn’t just a male problem. Both sexes have immoral fantasies. Women might be more captured by romantic literature and men by erotic pictures, but the end result is the same—you are committing adultery in your thought life” (David Powlison, “Breaking Pornography Addiction”). Jesus died on the cross, to deliver us from the penalty of lust, and also to purify our hearts, so that we begin in this life to learn by His Holy Spirit to be sexually pure (chaste), whether in marriage or in single life. “For this is the will of God, your sanctification; that you should abstain from sexual immorality” (1 Thess. 4:3-5). “The design of this commandment is the preservation of chastity… and the guarding of marriage, or keeping it holy” (Ursinus, 590).
The seventh commandment forbids all sexual impurity (unchastity), including fornication (sexual intercourse between people not married to each other), homosexuality (sexual intercourse between people of the same sex), incest (sexual intercourse with a parent, child, sibling, or grandchild), bestiality (sex with an animal), and polygamy (having more than one spouse at the same time). “Do not be deceived: neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And such were some of you. But you were washed, but you were sanctified, but you were justified” (1 Cor. 6:9-11). Only the Lord Jesus Christ can deliver us from both the penalty and addiction of sexual impurity, so that we learn to love chastity and loathe unchastity with our whole heart (Ps. 119:127-128).
God hates lust not only because it spoils His image in mankind, but especially because it destroys the marriage relationship. “Marriage is a lawful and indissoluble union between one man and one woman, instituted by God [Gen. 2:18-25; Matt. 19:4-6];” “that it might be the means of perpetuating and multiplying the human race in a lawful manner [Gen. 1:28];” that it might be the means to “gather to Himself out of the whole human race, thus lawfully propagated, an everlasting church, which shall rightly know and worship Him [Gen. 17:7; Mal. 2:14-15; 1 Cor. 7:14];” “that it might be an image or resemblance of the union between Christ and the church [Eph. 5:30-32];” and “that wanton and wandering lusts might in this way be avoided [1 Cor. 7:1-5] (Ursinus, 592-593). “Marriage is honorable among all, and the [marriage] bed undefiled [see the Song of Solomon]; but fornicators and adulterers God will judge” (Heb. 13:4). God “hates divorce” (Mal. 2:16). But He does permit divorce in the case of “sexual immorality” (Matt. 19:9) and in the case of an unbelieving spouse deserting their believing spouse: “if the unbeliever departs, let him depart” (1 Cor. 7:15). “Actions which are tantamount to desertion constitute adequate grounds for divorce. For example, the deliberate and unrepentant withholding of food, clothing, and sexual relations,” or “spousal abuse which is life-threatening or destructive of the “cleaving” aspect of marriage [Exodus 21:10-11] … Remarriage is lawful for persons divorced on biblical grounds [Matt. 19:9; 1 Cor. 7:15]” (RCUS paper on Divorce and Remarriage).
109. Does God forbid nothing more in this commandment than adultery and such gross sins?
Since both our body and soul are temples of the Holy Spirit, it is His will that we keep both pure and holy; therefore, He forbids all unchaste actions, gestures, words, thoughts, desires, and whatever may entice thereto.
In order for us to keep our body and soul sexually pure, we must remember that the Holy Spirit lives in us, which means that our body and soul are a temple of the Holy Spirit. He lives in us to sanctify us, to purify our hearts, so that we may more and more die unto sin and lead holy and blameless lives. “Flee sexual immorality. Every sin that a man does is outside the body, but he who commits sexual immorality sins against his own body. Or you not know that your body is the temple of the Holy Spirit who is in you, whom you have from God, and you are not your own? For you were bought at a price; therefore, glorify God in your body and in your spirit, which are God’s” (1 Cor. 6:18-20). This is why He commands us to be holy: “as He who called you is holy, you also be holy in all your conduct” (1 Pet. 1:15). He intends to use the command to be holy to make us holy, in answer to Jesus’ prayer: “Sanctify them by Your truth. Your Word is truth” (John 17:17; cf. Ps. 119:9; Rom. 12:2; Eph. 5:26). Through prayerful reading of God’s Word, we desire to obey God’s Word. “Make me walk in Your commands, for I delight in it. Incline my heart to Your testimonies, and not to covetousness. Turn away my eyes from looking at worthless things” (Ps. 119:35-37). Our lust will not condemn us or separate us from God’s love, but it still grieves the Holy Spirit who dwells in us; “do not grieve the Holy Spirit of God” (Eph. 4:30). It is because we love God that we do not want to grieve Him with our sexual sins.
It is also because we fear God that we avoid “all unchaste actions, gestures, words, thoughts, desires, and whatever may entice thereto.” Just because our heavenly Father will not punish us in hell for our sins, does not mean He will not discipline us for our sins in this life. “Whom the LORD loves He chastens” (Heb. 12:5; cf. Ps. 99:6-8; 1 Cor. 10:8). The Lord chastened Samson (Judges 16) and David (2 Samuel 12) for their sexual sins. “As many as I love, I rebuke and chasten. Therefore, be zealous and repent” (Rev. 3:19). “By the fear of the LORD one departs from evil” (Prov. 16:6; cf. Gen. 39:7-12). “Nothing is more powerful to overcome temptation than the fear of God” (Calvin). “Therefore … beloved, let us cleanse ourselves from all filthiness of the flesh and spirit, perfecting holiness in the fear of God” (2 Cor. 7:1). “The eyes of the Lord are in every place, keeping watch on the evil and the good” (Prov. 15:3). “I have made a covenant with my eyes; why then should I look upon a young woman?” (Job 31:1). “I will set nothing wicked before my eyes” (Ps. 101:2-3). We do not need to look at pornography in order to have sexual fantasies, but pornography will provide plenty of fuel for the fire. Better not to strike the match. An ounce of prevention is better than a pound of cure (Gal. 6:10). “If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteous” (1 John 1:9).