C. S. Lewis had to make the journey from atheism to Christianity. In his book Mere Christianity, he explains how he came up against the lack of logic in his atheistic position:
[When I was an atheist] my argument against God was that the universe seemed so cruel and unjust. But how had I got this idea of just and unjust? A man does not call a line crooked unless he has some idea of a straight line. What was I comparing this universe with when I called it unjust? If the whole show was bad and senseless from A to Z, so to speak, why did I, who was supposed to be part of the show, find myself in such violent reaction against it? . . .
Thus in the very act of trying to prove that God did not exist—in other words, that the whole of reality was senseless—I found I was forced to assume that one part of reality—namely my idea of justice—was full of sense. Consequently atheism turns out to be too simple. If the whole universe has no meaning, we should never have found out that it has no meaning.