The question is more difficult to answer than appears, because most atheists take the position that religious adherents are supposed to prove that their particular God exists, and that God is required to do so, when you ask him. The dogmatic way the religions are structured creates this attitude.
Christianity pretends to be a religion of proof and logic, where God will demonstrate himself by miracles, if you ask. We have many Christians coming here, who assert that God will answer, if you pray hard enough. They also rationalize their belief by the prophecies in Isaiah and Daniel, as if it's a 1-2-3 formula. Being logical, atheists then expect-back, that the Bible should be accurate, non-forged and non-contradictory.
Why should God show himself? Does God show himself to a hamster or beetle? That's ridiculous, a hamster is just required to be a hamster, with no intervention from God. The question is : are humans just required to be humans?
Being an odd species, we have no idea what being a human is really supposed to be. Does a human watch TV all day, while eating pizza? The bulk of religion focusses on proscriptive imaginings of what you are supposed to do, to please a God, who is obviously not going to reveal himself, or tell us what to do.
Intermingled with this, is the imaginary quest, that says a human is more equipped to "find" God than a hamster, and as well as being human, we also have the added pressure to "find" God, and tell others that we have found him, even though, from an evolutionary point of view, we may not have developed the faculties to do it. We have no qualms saying that a hamster is obviously not equipped to find God, but then ascribe this potential to all humans.
Thus, the question of the OP could be similar to asking a bronze age shepherd: what would it take to change your mind about Quantum Loop Gravity?
The shepherd could simply accept your word for it, or he could become a hermit, and go on a life-long quest, to explore quantum physics. This would be known as the hard path.
In summary, it's only likely that I would change my mind about God, if he direct injected some understanding into my mind, and made me believe in him. This seems to be the way that most religious fanatics work, anyway.