This book provides a detailed, updated exposition and defense of five of the historically most important (but in recent years largely neglected) philosophical proofs of God's existence: the Aristotelian, the Neo-Platonic, the Augustinian, the Thomistic, and the rationalist. It also offers a thorough treatment of each of the key divine attributes -- unity, simplicity, eternity, omnipotence, omniscience, perfect goodness, and so forth -- showing that they must be possessed by the God whose existence is demonstrated by the proofs. Finally, it answers at length all of the objections that have been leveled against these proofs. This work provides as ambitious and complete a defense of traditional natural theology as is currently in print. Its aim is to vindicate the view of the greatest philosophers of the past-- thinkers like Aristotle, Plotinus, Augustine, Aquinas, Leibniz, and many others -- that the existence of God can be established with certainty by way of purely rational arguments. It thereby serves as a refutation both of atheism and of the fideism that gives aid and comfort to atheism.