The medievals loved to say that God wrote two books: nature and Scripture. And since he is the author of both books, and since this Teacher never contradicts himself, these two books never contradict each other. And since this God who never contradicts himself also gave us the two truth detectors, faith and reason, it follows that faith and reason, properly used, never contradict each other. Therefore, all heresies are contrary to reason. Not all the truths of faith can be proved by reason, but all arguments against the truths of faith can be disproved by reason.
--Peter Kreeft, Socrates Meets Jesus: History's Greatest Questioner Confronts the Claims of Christ