We must always remember that sin muddles. Even though we live in a sex-crazed society, it does not follow from this that we understand sex, or sexual morality. The “openness” advocated by so many actually blurs the understanding. In such a situation, God’s law illumines; disobedience results not only in sexual immorality, but also sexual immaturity, ignorance, and idiocy. Sexual disobedience is not liberating or enlightening — it is vandalism. Just as there may in a sense be an exhilaration of sorts in spray-painting someone’s building in the middle of the night, so there is exhilaration in adultery. But it is vandalism regardless, and God’s Word declares plainly that “You shall not commit adultery” (Ex. 20:14).
What should be our motives to purity? Obedience to God’s sexual law is very important. Job describes adultery as “wickedness” and “iniquity deserving of judgment” (Job 31:11). Scripture sets many godly incentives before us to keep us sexually pure.
The first is the fear of God. “The mouth of an immoral woman is a deep pit; he who is abhorred by the Lord will fall there” (Prov. 22:14). Joseph appeals to this as he resists an attempted seduction “How then can I do this great wickedness, and sin against God?” (Gen. 39:9). God witnesses every sexual disobedience (Jer. 29:23). “I will come near you for judgment; I will be a swift witness against . . . adulterers” (Mal. 3:5).
Another motive should be desire for salvation. “Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites . . .” (1 Cor. 6:9). In Hebrews 13:4, we are bluntly told that “fornicators and adulterers God will judge.”
The Bible is plain on this subject “her guests are in the depths of hell” (Prov. 9:18) “Her house is the way to hell, descending to the chambers of death” (Prov. 7:27).
A third motive is the love of a good wife. The godly husband is commanded to rejoice in his wife sexually (Prov. 5:18). The marriage bed is honorable (Heb. 13:4); the power of a biblical (i.e. good) sexual relationship is tremendous. Many waters cannot quench love, nor can the floods drown it. If a man would give for love all the wealth of his house, it would be utterly despised (Song 8:7).
Another motive to purity is fear of slavery and moral stupidity. “For they shall eat, but not have enough; they shall commit harlotry, but not increase; because they have ceased obeying the Lord. Harlotry, wine, and new wine enslave the heart” (Hos. 4:10-11).
Yet another motive is concern for human dignity. Scripture repeatedly compares men in the grip of this sin to brute beasts (Jer. 5:8). Man is not like a beast simply because he shares with them a sexual nature; he is like them when he is driven by it.
Then there is concern for reputation. “Whoever commits adultery with a woman lacks understanding; he who does so destroys his own soul. Wounds and dishonor he will get, and his reproach will not be wiped away” (Prov. 6:32-33).
Sexual sin is also costly financially. A man should be concerned about financial ruin. “For by means of a harlot a man is reduced to a crust of bread; and an adulteress will prey upon his precious life” (Prov. 6:26; cf. 5:10). Remember the younger brother in Christ’s parable reduced himself to pig food by squandering his heritage on whores (Luke 15:30).
And finally, a scriptural motivation to purity is a concern for health. “And you mourn at last, when your flesh and your body are consumed, and say: ‘How I have hated instruction, and my heart despised correction!'” (Prov. 5:11).
These are all reasons to be sexually pure, but good reasons are obviously not enough. What are some of the God-given means to that end? All the following have to be considered in the context of faithful worship of God, and regular attendance upon His principal means of grace, which are Word and sacrament.
First, watch your doctrine. “and by fear of the Lord one departs from evil” (Prov. 16:6). “I have seen your adulteries . . .” (Jer. 13:27). God is present with you in all that you do; you cannot escape His omniscience. Because this is disconcerting, it is easy for some who want to slip off to some dark corner to begin to think that “God does not see.”
Second, watch your heart. Do not begin to think that adultery is only located “out there” in the world, and has been foisted upon you. “For out of the heart proceed . . . adulteries, fornications . . .” (Matt. 15:19). Peter begs Christians to “abstain from fleshly lusts which war against the soul” (1 Pet. 2:11).
Third, love your wife. St. Paul teaches that “because of sexual immorality, let each man have his own wife, and let each woman have her own husband. Let the husband render to his wife the affection due her, and likewise also the wife to her husband” (1 Cor. 7:2-3).
Fourth, watch your eyes. “Having eyes full of adultery . . .” (2 Pet. 2:14). Job said, “I have made a covenant with my eyes; why then should I look upon a young woman?” (Job 31:1).
Fifth, listen to wise parents. “My son, give me your heart, and let your eyes observe my ways. For a harlot is a deep pit, and a seductress is a narrow well. She also lies in wait as for a victim, and increases the unfaithful among men” (Prov. 23:26-28).
And sixth, cultivate a life of overall self-control. “When I had fed them to the full, then they committed adultery and assembled themselves by troops in the harlots’ houses. They were like well-fed lusty stallions; every one neighed after his neighbor’s wife” (Jer. 5:7-8; cf. Eze. 16:49). St. Paul teaches the value of self-discipline. “For I discipline my body and bring it into subjection, lest, when I have preached to others, I myself should become disqualified” (1 Cor. 9:27). And discipline in one area transfers to another.