He realized his lack of knowledge formed the basis of his unbelief. As Lewis explained in a letter written shortly after his transition, “What has been holding me back . . . has not been so much a difficulty in believing as a difficulty in knowing . . . you can’t believe a thing while you are ignorant what the thing is.”

Nicholi, Armand (2002-04-03). The Question of God (p. 93). Simon & Schuster, Inc.. Kindle Edition.

If he had all the answers, why did the question of God’s existence continue to preoccupy him? Perhaps Lewis would say we can never explain away God. Nor can we find rest until that deep-seated desire (experienced by both Freud and Lewis) is satisfied.

Nicholi, Armand (2002-04-03). The Question of God (p. 51). Simon & Schuster, Inc.. Kindle Edition.


Lewis said that when he was an atheist, his life also was full of contradictions. He writes: “I was at this time living, like so many Atheists . . . in a whirl of contradictions. I maintained that God did not exist. I was also very angry with God for not existing. I was also equally angry with Him for creating a world . . . why should creatures have the burden of existence forced on them without their consent?” Even as an atheist, Lewis realized his ambivalence toward God—a part of him wanting desperately that God not exist, another part strongly desiring His existence.

Nicholi, Armand (2002-04-03). The Question of God (pp. 51-52). Simon & Schuster, Inc.. Kindle Edition.

The reason you doubt Christianity's Belief A is because you hold unprovable Belief B. Every doubt, therefore, is based on a leap of faith. Some people say, "I don't believe in Christianity because I can't accept the existence of moral absolutes. Everyone should determine moral truth for him-or herself." Is that a statement they can prove to someone who doesn't share it? No, it is a leap of faith, a deep belief that individual rights operate not only in the political sphere but also in the moral. There is no empirical proof for such a position. So the doubt (of moral absolutes) is a leap. 


- The Reason for God, Tim Keller, locations 221-31 

The only way to doubt Christianity rightly and fairly is to discern the alternate belief under each of your doubts and then to ask yourself what reasons you have for believing it. How do you know your belief is true? It would be inconsistent to require more justification for Christian belief than you do for your own, but that is frequently what happens. In fairness you must doubt your doubts. The thesis is that if you come to recognize the beliefs on which your doubts about Christianity are based, and if you seek as much proof for those beliefs as you seek form Christians for theirs - you will discover that your doubts are not as solid as they first appeared. 

- The reason for God, Tim Keller, locations 221 -31