The way I like to understand it is that God and Existence itself are the same thing. Nothing can exist without God, because God IS Existence. There can be no Existence without God, because God IS Existence.

Asking where God came from is like asking where Existence came from. Existence could not come from somewhere, because that would imply there was Existence before Existence, which is not possible. Thus Existence had to always exist to begin with, meaning God had to always exist to begin with.

Yes that is hard to imagine, but that is because of our limited comprehension and knowledge of eternal facts.

Anyone who thinks we are all gods, or that everything came to be on its own, from absolute nothing to human consciousness, is just fooling themselves so they can fell better about their sins.