“Christianity places a premium on the absolute truthfulness and trustworthiness of God, so understanding doubt is extremely important to a Christian. Of course, faith is much more than the absence of doubt, but to understand doubt is to have a key to a quiet heart and a quiet mind. Anyone who believes anything will automatically know something about doubt. But the person who knows why he believes is also in a position to discover why he doubts. The Christian should be such a person.
“Not only does a Christian believe, he is a person who ‘thinks in believing and believes in thinking,’ as Augustine expressed it. The world of Christian faith is not a fairy-tale, make-believe world, question-free and problem-proof, but a world where doubt is never far from faith’s shoulder.
“Consequently, a healthy understanding of doubt should go hand in hand with a healthy understanding of faith. We ourselves are called in question if we have no answer to doubt. If we constantly doubt what we believe and always believe-yet-doubt, we will be in danger of undermining our personal integrity, if not our stability. But if ours is an examined faith, we should be unafraid to doubt. If doubt is eventually justified, we were believing what clearly was not worth believing. But if doubt is answered, our faith has grown stronger still. It knows God more certainly and it can enjoy God more deeply.”
— Os Guinness, In Two Minds: The Dilemma of Doubt and How to Resolve It