C.S. Lewis, Mere Christianity; Book III, Chapter 11 (excerpt)

“The Christian does not think God will love us because we are good, but that God will make us good because He loves us.” [C.S. Lewis, not in this excerpt]

No man knows how bad he is till he has tried very hard to be good. A silly idea is current that good people do not know what temptation means. This is an obvious lie. Only those who try to resist temptation know how strong it is. After all, you find out the strength of the German army by fighting against it, not by giving in. You find out the strength of a wind by trying to walk against it, not by lying down. A man who gives in to temptation after five minutes simply does not know what it would have been like an hour later. That is why bad people, in one sense, know very little about badness. They have lived a sheltered life by always giving in. We never find out the strength of the evil impulse inside us until we try to fight it: and Christ, because He was the only man who never yielded to temptation, is also the only man who knows to the full what temptation means — the only complete realist.

A man who starts anxiously watching to see whether he is going to sleep is very likely to remain wide awake.

Now we cannot, in that sense, discover our failure to keep God’s law except by trying our very hardest (and then failing). Unless we really try, whatever we say there will always be at the back of our minds the idea that if we try harder next time we shall succeed in being completely good. Thus, in one sense, the road back to God is a road of moral effort, of trying harder and harder. But in another sense it is not trying that is ever going to bring us home. All this trying leads up to the vital moment at which you turn to God and say, “You must do this. I can’t.” Do not, I implore you, start asking yourselves, “Have I reached that moment?” Do not sit down and start watching your own mind to see if it is coming along. That puts a man quite on the wrong track. When the most important things in our life happen we quite often do not know, at the moment, what is going on. A man does not always say to himself, “Hullo! I’m growing up.” It is often only when he looks back that he realises what has happened and recognises it as what people call “growing up.” You can see it even in simple matters. A man who starts anxiously watching to see whether he is going to sleep is very likely to remain wide awake. As well, the thing I am talking of now may not happen to every one in a sudden flash — as it did to St Paul or Bunyan: it may be so gradual that no one could ever point to a particular hour or even a particular year. And what matters is the nature of the change in itself, not how we feel while it is happening. It is the change from being confident about our own efforts to the state in which we despair of doing anything for ourselves and leave it to God.

Not hoping to get to Heaven as a reward for your actions, but inevitably wanting to act in a certain way because a first faint gleam of Heaven is already inside you.

Thus if you have really handed yourself over to Him, it must follow that you are trying to obey Him. But trying in a new way, a less worried way. Not doing these things in order to be saved, but because He has begun to save you already. Not hoping to get to Heaven as a reward for your actions, but inevitably wanting to act in a certain way because a first faint gleam of Heaven is already inside you. The other set were accused of saying, “Faith is all that matters. Consequently, if you have faith, it doesn’t matter what you do. Sin away, my lad, and have a good time and Christ will see that it makes no difference in the end.” The answer to that nonsense is that, if what you call your “faith” in Christ does not involve taking the slightest notice of what He says, then it is not Faith at all — not faith or trust in Him, but only intellectual acceptance of some theory about Him.

“If we find ourselves with a desire that nothing in this world can satisfy, the most probable explanation is that we were made for another world.” [C.S. Lewis, not in this excerpt]