This is a quote from one of Cardinal Ratzinger's books.
The decision to believe in God is ultimately a decision in favour of reason and a decision about whether good and evil, truth and untruth, are merely subjective categories or reality. In this sense, in the beginning there is faith, but a faith that first acknowledges the dignity and scope of reason. Thinking and living are no longer separable when man confronts the ultimate questions. The decision for God is simultaneously an intellectual and an existential decision – each determines the other reciprocally. For us the problem is whether the world comes from an irrational source, so that reason would be nothing but a "by-product " of the development of the world, or whether the world comes from reason, so that it's criterion and its goal is reason. A reason that has its origin in the irrational and is itself ultimately irrational does not offer a solution to our problems. Only that creative reason which has manifested itself as love in the crucified God can truly show us what life is. It is an obvious fact that the rational character of the universe cannot be explained rationally on the basis of something irrational! This is why the Logos (the word of God, that word which he issued to create the world in the creation stories found in Genesis , and the word that became flesh in the person of Jesus) that is at the origin of all things remains more than ever the best hypothesis, although this is of course a hypothesis that demands that we give up a position where it is we who are in charge and that we take the risk of assuming the position if the humble listeners. That is to say that everything is a stream of thought. The creative spirit is the origin and the sustaining ground of all things. All that is, is by its origin intelligible, because it comes from creative reason.