All right, Christianity will do you good a great deal more good than you ever wanted or expected. And the first bit of good it will do you is to hammer into your head (you won’t enjoy that!) the fact that what you have hitherto called ‘good’ — all that about ‘leading a decent life’ and ‘being kind’ — isn’t quite the magnificent and all-important affair you supposed. It will teach you that in fact you can’t be ‘good’ (not for twenty-four hours) on your own moral efforts. And then it will teach you that even if you were, you still wouldn’t have achieved the purpose for which you were created. Mere morality is not the end of life. You were made for something quite different from that. J. S. Mill and Confucius (Socrates was much nearer the reality) simply didn’t know what life is about. The people who keep on asking if they can’t lead a decent life without Christ, don’t know what life is about; if they did they would know that ‘a decent life’ is mere machinery compared with the thing we men are really made for. Morality is indispensable: but the Divine Life, which gives itself to us and which calls us to be gods, intends for us something in which morality will be swallowed up. We are to be re-made. All the rabbit in us is to disappear — the worried, conscientious, ethical rabbit as well as the cowardly and sensual rabbit. We shall bleed and squeal as the handfuls of fur come out; and then, surprisingly, we shall find underneath it all a thing we have never yet imagined: a real Man, an ageless god, a son of God, strong, radiant, wise, beautiful, and drenched in joy.
‘When that which is perfect is come, then that which is in part shall be done away’ (1 Cor 13:10). The idea of reaching ‘a good life’ without Christ is based on a double error. Firstly, we cannot do it; and secondly, in setting up ‘a good life’ as our final goal, we have missed the very point of our existence. Morality is a mountain which we cannot climb by our own efforts; and if we could we should only perish in the ice and unbreathable air of the summit, lacking those wings with which the rest of the journey has to he accomplished. For it is from there that the real ascent begins. The ropes and axes are ‘done away’ and the rest is a matter of flying.
– from C.S. Lewis, “Man or Rabbit?”