The greatest Christian men to have ever lived, were not great because of their theological prowess alone, but because their theology made a deep impact in their own lives. I remember reading some years ago A.N. Wilson’s massive biography of C.S. Lewis. As a non-christian Wilson cannot see how the Christian faith affects a man after conversion. He focuses the majority of his description of Lewis to his earlier unconverted days. However, as has been mentioned before, a full birth only occurs when the birth from above takes place. All that occurs prior to the new birth is unworthy to a certain extent. It is in this new life that Lewis demonstrates the power of the gospel. For our sake, he has shared his wisdom.
Two areas where Lewis’ insights are gloriously welcome are the nature of the heart and the virtue of persevering. St. Paul regards himself the chief of sinners. He was seeking a higher goal, a goal that would lead him to ultimate glorification. But for sanctification to occur, one must know the self, and to truly know the self, we need to see it before God’s Holiness. The language of sanctification is a more Protestant term. As far as I know I have not seen that language in Lewis’ writing. Nevertheless, you will find him using the idea of “better,” to express what we mean as sanctification, or spiritual growth. With this is mind, Lewis analyzes the nature of man:
When a man is getting better he understands more and more clearly the evil that is still left in him. When a man is getting worse he understands less and less his own badness.
This is not difficult theology, but difficult to live. As a man grows in his faith, he begins to see the darkness of his own sin. On the other hand, the one who does not grow, begins to think highly of himself and haughtiness overcomes him. He becomes more confident of his sins, and repenting is no longer an option. The proud man has nothing to repent of since he cannot see his own sin.
Those who persevere in their faith are aware of their constant battles with sin and their longing to abandon their habits. For men, nothing is so troubling as the sins of the heart, particularly as they relate to sexuality. Overcoming this sin is like beating on the water; the water always resurfaces. The same is true of sexual temptations. Christians are to flee temptations, as Joseph did. When we break the seventh commandment we have fallen for the trap of the woman in Proverbs 7, and face the guilt and consequences of that sin.
Our society demands that we fall for this great sin. Our pagan society is waiting every second of the day for another Ted Haggard scandal to embarrass the Christian church. But they do not simply sit in their golden chairs; they actively work to see that that Christian failure takes place. In Lewis’ words:
Poster after poster, film after film, novel after novel, associate the idea of sexual indulgence with the ideas of healthy, normality, youth, frankness, and good humor.
The tactic is simple as Lewis mentions, associate that which is evil with that which is good. But this devilish trap must not prevail. We need to be constantly aware of our own depravity and need of grace. The unfortunate aspect of this entire dimension is that we are never going to be fully free from temptations. Indeed, we will fall, if not in deed, in our hearts. But there is recovery for those who persevere.
After each failure, ask forgiveness, pick yourself up, and try again. Very often what God first helps us towards is not the virtue of itself but just this power of always trying again.
Persevering is a virtue and our salvation rests in the grace of God to discipline His own and prepare them to walk once again when they have fallen.
 The Apostle Paul spoke of the days in which he persecuted the Christians, but now all those things are left behind, so that he may pursue the excellencies of Christ.
 This latter is not one of the virtues Lewis lists, but I have chosen such for clarity purpose.
 Mere Christianity, pg.88
 Ibid. 93.
 Lewis, 94.