It’s impossible to prove the existence of God, likewise it’s impossible to prove that He doesn’t exist.
Theists, and especially evangelical Christians, rely on tautological or circular reasoning. They will engage in lengthy rhetorical flights, but their argument boils down to:
The Bible is the Word of God and the Bible says there is a God, how can a mere mortal disagree with God? I believe there’s a God because the Bible is the Word of God.
Gravity is the invisible force that keeps us on the surface of the Earth, and the Earth in orbit around the Sun. From Galileo to the present day the reality of gravity has been conclusively proven by scientific means. Even an idiot will realize that gravity is real when a pine cone falls off a tree and hits him on the head.
God is also an invisible force, unfortunately there is no way to prove His existence by scientific means or by rhetorical flourish. When a Christian says “I know that God is real because he changed my life”, we must adopt the attitude that he is entitled to his belief, regardless if it’s based on emotion and not on logic.
When Christians declares that they talk to the Almighty, we must respect their faith without being condescending.
However, my patience runs out when they insist that God talks back to them. Whenever a believer exclaims, “God told me…”, I instantly turn a deaf ear.
Of course, God doesn’t talk to anyone, and whenever anyone prefaces their remarks by uttering, “God told me” they are just trying to give more weight to their words by ascribing them to God.
When you hear anyone, whether he/she is a minister or the slob sitting next to you at the bar, say “God told me”, you have every right to tell them: Shut the fuck up.