Challenge.

Ramishvili, C.S. Lewis at Magdalene College, 1950

Scrupulous care to preserve the Christian message, as something distinct from one’s own ideas, has one very good effect upon the apologist himself. It forces him, again and again, to face up to those elements in original Christianity which he personally finds obscure or repulsive. He is saved from the temptation to skip or slur or ignore what he finds disagreeable. And the man who yields to that temptation will, of course, never progress in Christian knowledge. For obviously the doctrines which one finds easy are the doctrines which give Christian sanction to truths you already knew. The new truth which you do not know and which you need must, in the very nature of things, be hidden precisely in the doctrine you least like and least understand. It is just the same here as in science. The phenomenon which is troublesome, which doesn’t fit in with the current scientific theories, is the phenomenon which compels reconsideration and thus leads to new knowledge. Science progresses because scientists, instead of running away from such troublesome phenomena or hushing them up, are constantly seeking them out. In the same way, there will be progress in Christian knowledge only as long as we accept the challenge of the difficult or repellent doctrines. A “liberal” Christianity which considers itself free to alter the faith whenever the faith looks perplexing or repellent must be completely stagnant. Progress is made only into a resisting material.

C.S. Lewis, from "Christian Apologetics"