Thoughts on Doubting Christianity by Timothy Keller
"A faith without some doubts is like a human body without any antibodies in it. People who blithely go through life too busy or indifferent to ask hard questions about why they believe as they do will find themselves defenseless against either the experience of tragedy or the probing questions of a smart skeptic. A person's faith can collapse almost overnight if she has failed over the years to listen to her own doubts, which should only be discarded after long reflection. Believers should acknowledge and wrestle with doubts—not only their own, but their friends' and neighbors'.
But even as believers should learn to look for reasons behind their faith, skeptics must learn to look for a type of faith hidden within their reasoning. All doubts, however skeptical and cynical they may seem, are really a set of alternative beliefs. You cannot doubt Belief A from a position of faith in Belief B. For example, if you doubt Christianity because 'There can't be just one true religion,' you must recognize that this statement is itself an act of faith. No one can prove it empirically, and it is not a universal truth that everyone accepts. If you went to the Middle East and said, 'There can't be just one true religion,' nearly everyone would say, 'Why not?' 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."
--from Timothy Keller, The Reason for God, Belief in an Age of Skepticism