Just recently, I was watching a DVD by Australian apologist Matt Fradd. He was describing his journey to God. In his high school days, he had become an agnostic, doubting whether one could know God or not. Transformed by attending a World Youth Day in Rome, he was caught on fire with the Holy Spirit, and moved his relationship with our Lord Jesus Christ to the center of his being. He tells a good tale, and with the Australian accent, he's automatically more interesting to listen to than most people. :)
But he had a quote from C.S. Lewis about faith which I found fascinating. The quote comes from Lewis' Mere Christianity which is a fantastic book for people who are questioning whether or not Jesus is the real thing. In re-reading the section of the book, I found an incredible and easy-to-understand discussion as to what faith is, and why we value it in the Church. I'll present some excerpts here, from chapter 11 of Book 3 of Mere Christianity.
Roughly speaking, the word Faith seems to be used by Christians in two sense or on two levels... In the first sense it means simply Belief--accepting or regarding as true the doctrines of Christianity. This is fairly simple. But what does puzzle people--at least it used to puzzle me--is the fact that Christians regard faith in this sense as a virtue. I used to ask how on earth it can be a virtue--what is there moral or immoral about believing or not believing a set of statements?....
What I did not see then--and a good many people do not see still--was this. I was assuming that if the human mind once accepts a thing as true it will automatically go on regarding it as true, until some real reason for reconsidering it turns up. In fact, I was assuming that the human mind is completely ruled by reason. But that is not so.... It is not reason that is taking away my faith: on the contrary, my faith is based on reason. It is my imagination and emotions [that take away my faith]. The battle is between faith and reason on one side and emotion and imagination on the other.
When you think of it you will see lots of instances of this. A man knows, on perfectly good evidence, that a pretty girl of his acquaintance is a liar and cannot keep a secret and ought not to be trusted: but when he finds himself with her his mind loses its faith in that bit of knowledge and he starts thinking, 'Perhaps she'll be different this time," and once more makes a fool of himself and tells her something he ought not to have told her. His senses and emotions have destroyed his faith in what he really knows to be true...
Now just the same thing happens about Christianity. I am not asking anyone to accept Christianity if his best reasoning tells him that the weight of the evidence is against it. That is not the point at which Faith comes in. But supposing a man's reason once decides that the weight of the evidence is for it. I can tell that man what is going to happen to him in the next few weeks. There will come a moment when there is bad news, or he is in trouble, or is living among a lot of other people who do not believe it, and all at once his emotions will rise up and carry out a sort of blitz on his belief. Or else there will come a moment when he wants a woman, or wants to tell a lie, or feels very pleased with himself, or sees a chance of making a little money in some way that is not perfectly fair: some moment, in fact, at which it would be very convenient if Christianity were not true. And once again, his wishes and desires will carry out a blitz. I am not talking of moments at which any real new reasons against Christianity turn up. Those have to be faced and that is a different matter. I am talking about moments when a mere mood rises up against it.
Now Faith, in the sense in which I am here using the word, is the art of holding on to things your reason has once accepted, in spite of your changing moods. For moods will change, whatever view your reason takes. I know that by experience. Now that I am a Christian I do have moods in which the whole thing looks very improbable: but when I was an atheist I had moods in which Christianity looked terribly probably. This rebellion of your moods against your real self is going to come anyway. That is why Faith is such a necessary virtue: unless you teach your moods 'where they get off', you can never be either a sound Christian or even a sound atheist, but just a creature dithering to and fro, with its beliefs really dependent on the weather and the state of its digestion. Consequently one must train the habit of Faith.