Dear Husband,

After reading the contributions and pleas of the earlier contributors to this series, there is little that I might add that does not fall under “vain repetition.” If your conscience is not strengthened to repel sexual temptations after you have read what they have written, how will anything that I add make a difference?

You can begin to see adultery for what it is by grasping how antithetical it is to faith. The sin of adultery screams out to the world that you don’t really believe God. Perhaps it will be helpful to make this clear. If you are contemplating adultery, consider at least four probing questions about what you believe.

1. Do you believe God sees all?

You don’t really believe God when he declares that you may “be sure your sin will find you out” (Numbers 32:23). If you think you can get away with it, just because you succeed (at least for a while) in hiding it from your contemporaries, as David did, you are acting as if God doesn’t exist, or doesn’t mean what he says.

Whether in this life, or on the last day, your sin will be exposed. To act as if that is not the truth is to disbelieve God Almighty. “No creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account” (Hebrews 4:13).

For the Christian, it is not only the fear of being caught by your peers that may rein in your sexual fantasies, but faith that God keeps his word, that he is not mocked, that no sin can be hidden from him.

2. Do you believe what God says about adultery?

“The sin of adultery screams out to the world that you don’t really believe God.”

You don’t really believe God when he depicts the deceit and wretchedness of adultery. Such depictions in Scripture are many. One recalls the distressing warnings of Proverbs (for example, Proverbs 6:20–7:27), the straightforward prohibition of adultery in the Decalogue (Exodus 20:14), the narrative depiction of adultery and its wretched results (for example, 2 Samuel 11–12), the many warnings against fornication and adultery in the New Testament, the shockingly close link between physical adultery and spiritual apostasy (so much so that God dares to depict himself through the prophecy of Hosea as the Almighty cuckold), and this contrasted with the narrative depiction of a faithful Joseph who successfully fights off sexual temptation, thereby avoiding fornication (on his part) and adultery (on the part of Potiphar’s wife in Genesis 39). 

The account of Joseph is particularly instructive. Joseph knows full well that if he and Potiphar’s wife have an affair, it means he is betraying Potiphar (Genesis 39:8–9). If two single people engage in illicit sex, that is bad enough. It is worse where one or both are married to another party: the betrayal of the partner or partners is grotesque — a kind of sexual theft.

More importantly, Joseph recognizes that the dimensions of the sin can be calculated only by seeing that adultery is sin against God (Genesis 39:9). Joseph does not pave the way to adultery by lining up his excuses in advance: it’s only a peccadillo, a moment of weakness, it’ll happen only once, and after all I am lonely and as a slave have no prospect of marriage, and perhaps God could use this liaison to win my release. No, he calls a spade a spade and perceives that if he were to commit adultery, the most offended party would be God: “How then can I do this great wickedness and sin against God?” (Genesis 39:9). This is the step that David failed to take until after his sin with Bathsheba was exposed (Psalm 51:4).

At the practical level, Joseph avoided the woman whenever he could: he was not the sort of womanizer who enjoyed seeing how close he could get to the fire without getting burned (Genesis 39:10). Most impressively, he was the sort of man who preferred to retain his purity even if it meant that others judged him to be immoral, rather than the sort who wanted to be a secret adulterer while everyone but his partner in immorality thought him to be pure (Genesis 39:11–20). If you choose to commit adultery, you show yourself to be the opposite: sneaky adultery is more precious to you than moral integrity. You are laughing at what God says.

The point is obvious. God speaks often on this subject, and if you are resolved to pursue adultery regardless of what he says, you testify that you do not believe him. You are a practical atheist.

3. Do you believe what God says about marriage?

So far I have highlighted the unbelief that sets aside God’s evaluation of adultery and ignores his open threats. But there is also a great array of passages that hold up marriage as being a wonderful thing, a gift from God, a creation ordinance, a picture of the relationship between Christ and the church, the site where relational depth is developed, the secure center for the rearing of offspring, the place to test what godly discipline looks like, the locus where one man and one woman unite and best complement each other for God’s glory and his people’s good. Not to understand and embrace these vistas springs from unbelief: you are not taking God at his word.

But, you may say, my marriage is not like that. My wife does not really love me anymore. We have grown apart; our interests have diverged. Mind you, if that were the way Christ treated the church when his interests grow apart from those of the church, we’d all be damned. All of us are called to live in a world still groaning under the curse, waiting for the final revelation of the sons of God (Romans 8:19).

That means there are single people who will never get married: have they been cheated? It means there are some Christians who face violent persecution: have they been betrayed? It means there are marriages that are wobbly and spouses who are unhappy: have they been robbed of pleasure, such that they have permission to betray their vows? Or, rather, have all of us been called to take up our cross and follow Jesus, assured that if we suffer with him, we will also reign with him (Romans 8:17; 2 Timothy 2:12)? 

In short, what we need is more faith — faith in the promises of God, in God’s depictions of the new heaven and the new earth, in the hope of the health of resurrection existence, in the unimaginable joy and holiness of the visio Dei. And with respect to sexual temptations, we must trust God’s words when he dares to depict the glory to come, amongst other things, as the wedding of the Lamb (Revelation 19:7): that is, the union of Christ and his people will bring such a spectacular intimacy that all previous intimacies, as lovely as they were, will be utterly eclipsed. Fifteen minutes into eternity, no Christian who was forced to live celibately in this life will be whining, “I was robbed!” No Christian who kept his vows will be harboring regrets that he didn’t give in and enjoy a little illicit sex on the side.

“Our union of Christ will bring such a spectacular intimacy that all previous intimacies will be utterly eclipsed.”

Not to see things this way simply means that we don’t believe what God says. Our faith is pathetically anemic. Maybe it is akin to the “faith” that James condemns — the “faith” that Satan and his cohorts exercise, a “faith” that can never save them. Satan believes there is one God (James 2:19); for that matter, he believes that Jesus rose from the dead, and that there is a final resurrection of the just and the unjust. But such faith has never saved a demon nor a human being. Saving faith is characterized not only by a valid object, but by trust, by self-abandonment to the words and ways of God, by happy and resolute reliance on God and his promises. Faith that merely recites the creeds but produces no fruit is the faith of demons.

4. Do you believe in God’s lavish grace?

One more display of unbelief is invariably connected with adultery. God promises to provide all the needed grace to overcome temptation (1 Corinthians 10:13). Better yet, he pours out his Spirit upon us, whose fruit in our lives includes “gentleness and self-control” (Galatians 5:23). So we are not to “gratify the desires of the flesh” (Galatians 5:16); we are to “keep in step with the Spirit” (Galatians 5:25). To turn our back on such lavish supplies of grace and strength is the rawest form of determined unbelief.

My dear brother, believe the gospel, not only its promises of forgiveness, but its instructions and depictions of the glory and promises of our lavish God.