While researching for a paper, I reviewed Lewis’ chapter concerning sexual morality in Mere Christianity. Lewis concludes the chapter with this word of warning:

Finally, though I have had to speak at some length about sex, I want to make it as clear as I possibly can that the centre of Christian morality is not here. If anyone thinks that Christians regard unchastity as the supreme vice, he is quite wrong. The sins of the flesh are bad, but they are the least bad of all sins. All the worst pleasures are purely spiritual: the pleasure of putting other people in the wrong, of bossing and patronising and spoiling sport, and back-biting; the pleasures of  power, of hatred. For there are two things inside me, competing with the human self which I must try to become. They are the Animal self, and the Diabolical self. The Diabolical self is the worse of the two. That is why a cold, self-righteous prig who regularly goes to church may be far nearer to hell than a prostitute. But, of course, it is better to be neither.

In his classically biting and convicting style, Lewis forces his reader to consider first the plank in his own eye. As Christians, we claim to subscribe to the ridiculously high standard of Christ, who declared that adultery starts in the heart, not in the sex act. This idea was not unique to the “new” ethic of Jesus; Proverbs 23.7 says, “for as he thinks in his heart, so is he.”

Our thoughts say much more about who we are as people and as disciples of Christ– like a blinding headache or paralysis are external symptoms of an internal brain disease, our actions are just outer symptoms of an inner heart disease called sin. The Pharisees were notorious for judging others by their actions, but Jesus reminded them that “the Lord sees not as man sees: man looks on the outward appearance, but the Lord looks on the heart” (1 Sam 16.7). So many times we judge those around us by their behaviors– or worse, by their behavior before they surrendered their hearts and their lives to Christ. We would do well to remember that in the eyes of God, “all have sinned and fall short of the glory of God” (Rom. 3.23). But even for those of us who have committed supposedly more grievous sins, Paul declares, “such were some of you. But you were washed, you were sanctified, you were justified in the name of our Lord Jesus Christ and by the Spirit of our God (1 Cor 6.11). In God’s accounting, sin is sin, and even the smallest sin in man’s eyes is an infinite insult requiring infinite separation from an infinitely holy God. Let us not forget that in more than one of Paul’s lists of sins which deny entrance to heaven, disobedience to parents, lying tongues, and envy are listed side by side with the “big sins” of murder and theft and sexual immorality.

Just as Lewis closed his chapter, we will do well to remember that we are not to remain in any sin. Previously in this chapter, Lewis discussed the difficulty of striving against sin and the benefit of fighting through and overcoming our temptations. He wrote:

For however important chastity (or courage, or truthfulness, or any other virtue) may be, this process [of fighting and overcoming temptation] trains us in habits of the soul which are more important still. It cures our illusions about ourselves and teaches us to depend on God. We learn, on the one hand, that we cannot trust ourselves even in our best moments, and, on the other, that we need not despair even in our worst, for our failures are forgiven. The only fatal thing is to sit down content with anything less than perfection.

May we never be content with anything less than perfection! Though we will never reach it this side of our glorification, may we never cease seeing it as our goal! May our single desire be that we would be holy as He is holy.