My "proof" is that I am a rational, sane person and that I have personally experienced and interacted with them- not only "talking" to me, but I have allowed some of them to enter my body and interact with others. Once you have met a God, you will never forget it. The experience is unlike anything else.

While this answer will not satisfy some scientists or atheists, I am fine with that. Not everyone will have the same experiences- and mindset determines what you are able to experience.