Furthermore, as C.S. Lewis so ably pointed out in Miracles , faith in God undergirds human reason. Consequently, if we suppose that God does not exist, then we have no epistemological basis upon which to believe that the faculty of reason is a valid indicator of truth. In a sense, we have no reason to trust our reason. Without faith in God, we live in a meaningless, absurd, irrational world in which we have no reason to think that the human faculty of reason is valid. On the other hand, if we are the product of a rational and loving God, who is both the Creator of the cosmos and the author of our reason, then we have a basis upon which to trust in the validity of reason.
Reason is supported by faith.
Faith and reason must ultimately stand in harmony, not in conflict. Reason and faith are thus interwoven in the philosophies of Augustine, Anselm, and Aquinas. These thinkers taught that reason alone is unbalanced and unhealthy and that faith alone is also unbalanced and unhealthy. Together, however, they make a person whole . Aquinas, Anselm, and Augustine thus sought the unity of reason and revelation, faith and philosophy, not their divorce.