Natural reason is sufficiently powerful and trustworthy when it operates within its proper sphere, but it is too weak to provide much illumination in the arena of natural theology and it is downright unreliable when used to pass judgment on the first principles of revealed theology. To be sure, philosophical inquiry unaided by divine revelation can help foster logical skills and intellectual habits that are required for the articulation of true wisdom within Christian theology; it can even provide Christian thinkers with new and useful conceptual resources. But it cannot on its own make any noteworthy progess toward providing us with the substance of absolute wisdom.
Freddoso, Ockham on Faith and Reason §