Sarah and I have been reading C.S. Lewis's Chronicles of Narnia together as part of school. We are currently on Book 4 (I go by the original order, not the new one), The Silver Chair. It contains one of the best descriptions of faith I have ever read. Lewis just knocks it out of the park with this one. The scene is the evil witch attempting to convince the heroes that Narnia is mere make-believe that they have conjured up, not real at all. Aslan is also a figment of their imaginations. Here is Puddleglum's response:
"...I won't deny any of what you've said. But there's one more thing to be said, even so. Suppose we have only dreamed, or made up, all these things--trees and grass and sun and moon and stars and Aslan himself. Suppose we have. Then all I can say is that, in that case, the made-up things seem a good deal more important that the real ones. Suppose this black pit of a kingdom of yours is the only world. Well, it strikes me as a pretty poor one. And that's a funny thing, when you come to think of it. We're just babies making up a game, if you're right. But four babies playing a game can make a play-world which licks your real world hollow. That's why I'm going to stand by the play world. I'm on Aslan's side even if there isn't any Aslan to lead it. I'm going to live as like a Narnian as I can even if there isn't any Narnia. So, thanking you kindly for our supper, if these two gentlemen and the young lady are ready, we're leaving your court at once and setting out in the dark to spend our lives looking for Overland. Not that our lives will be very long, I should think; but that's small loss if the world's as dull a place as you say."
There are many who would claim that Christianity is a myth, a child's fairy tale. When you are facing discouragement and despair, when you are hearing the witch whispering in your ear and you are starting to believe her, when this "black pit of a kingdom" seems to be all there is, remember Puddleglum's words. It is worth it to live as a Narnian and to follow Aslan. The child's make-believe completely trumps the real world every time.