Here's something that I think has been overlooked so far (I may have missed it on an earlier page). If you have proof of a god, then you have knowledge that it exists, and therefore it is impossible to have faith in it. It's absurd to claim to have faith that 2+2=4 or that distilled water boils at 100 °C @ 1 atm (sea level). The evidence for either is overwhelming, so it is knowledge. If you have doubts about either one, there's a way to test it out. However, faith is essential to the Abrahamic religions. So if you have proof, you have destroyed faith.
Hebrews 11:6: "Without faith it is impossible to please [God], for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him."
Therefore, by claiming to have proof, someone would be setting him/herself up as the Antichrist. Prove your god and you'll burn in hell for it.