Occasionally, perhaps, even some of the traditional proofs for the existence of God have been interpreted as providing conclusive evidence for their theistic conclusions. From the outset, however, we must recognize that it is a mistake so to regard them, not because we know before we even begin that they do not prove anything, but rather because we know that there are no philosophical beliefs anywhere that are supported by conclusive evidence.
To expect indubitable premises and rigorous deductive validity from the traditional proofs [for God’s existence] is to expect too much. No philosophical proofs of anything rest on indubitable premises. Philosophical proofs simply cannot meet such exacting requirements, but this is not to make lame excuses for sloppy thinking.
Quoted from Ronald Nash, Life’s Ultimate Questions: An Introduction to Philosophy (Zondervan: 1999), p. 290