The question before each of us is not ‘Can someone lead a good life without Christianity’?’ The question is, ‘Can I?’
…. [T]he man who asks me, ‘Can’t I lead a good life without believing in Christianity?’ …. is really asking. ‘Need I bother about it? Mayn’t I just evade the issue, just let sleeping dogs lie, and get on with being “good”? Aren’t good intentions enough to keep me safe and blameless without knocking at that dreadful door and making sure whether there is, or isn’t someone inside?’
To such a man it might be enough to reply that he is really asking to he allowed to get on with being ‘good’ before he has done his best to discover what good means. But that is not the whole story. We need not inquire whether God will punish him for his cowardice and laziness; they will punish themselves. The man is shirking. He is deliberately trying not to know whether Christianity is true or false, because he foresees endless trouble if it should turn out to he true. He is like the man who deliberately ‘forgets’ to look at the notice hoard because, if he did, he might find his name down for some unpleasant duty. He is like the man who won’t look at his bank account because he’s afraid of what he might find there. He is like the man who won’t go to the doctor when he first feels a mysterious pain, because he is afraid of what the doctor may tell him.
The man who remains an unbeliever for such reasons is not in a state of honest error. He is in a state of dishonest error, and that dishonesty will spread through all his thoughts and actions: a certain shiftiness, a vague worry in the background, a blunting of his whole mental edge, will result. He has lost his intellectual virginity. Honest rejection of Christ, however mistaken, will be forgiven and healed ‘Whosoever shall speak a word against the Son of man, it shall he forgiven him’ (Luke 12:10). But to evade the Son of Man, to look the other way, to pretend you haven’t noticed, to become suddenly absorbed in something on the other side of the street, to leave the receiver off the telephone because it might he He who was ringing up. To leave unopened certain letters in a strange handwriting because they might he from Him — this is a different matter. You may not he certain yet whether you ought to be a Christian; but you do know you ought to be a Man, not an ostrich, hiding its head in the sand.
C.S. Lewis, “Man or Rabbit?” published as a pamphlet for the Student Christian Movement in Schools (probably 1946) and God in the Dock (Eerdmans: 1970) 110-111.