I did grasp it. But, as you point out, your idea that 'it can't be proven' is predicated on a belief that he's human. It could still be proven that God exists, and that you are wrong in your belief. That being said, if this guy-that-looks-human snapped his fingers and turned the world inside out, and day into night - "God" would still rise to the top of my list of possibilities. 100 mile tall... That is a belief. You don't know he does not exist. None of us do. Not even us atheists.