Arthur Brooks: We cannot expect ever to settle the argument over the existence of God. Just as we should continue to question theories, hypotheses, and assumptions in every field of science, we should interrogate religious and philosophical beliefs. By the same token, however, we should also exercise skepticism about our unbeliefs based on what we cannot perceive directly. To dismiss something for the fact of its invisibility is a mistake. Instead, intellectual integrity should make us open to indirect evidence that comes from beyond the realm of ordinary observation.