The first independent idea about religion I ever remember thinking was a question I asked my father, an elder in the church, a good and wise and holy man. I was amazed that he couldn't answer it. "Why do we Calvinists have the whole truth and no one else? We're so few. How could God leave the rest of the world in error? Especially the rest of the Christian churches?" Since no good answer seemed forthcoming, I then came to the explosive conclusion that the truth about God was more mysterious—more wonderfully and uncomfortably mysterious—than anything any of us could ever fully comprehend. (Calvinists would not deny that, but they do not usually teach it either. They are strong on God's "sovereignty," but weak on the richness of God's mystery.) That conviction, that the truth is always infinitely more than anyone can have, has not diminished. Not even all the infallible creeds are a container for all that is God.
Source: Peter Kreeft - Hauled aboard the Ark, http://www.peterkreeft.com/topics/hauled-aboard.htm