During an interview late in life, Carl Jung said, when asked if he believed in God, that "I don't need to believe. I know." I think I know what Jung was getting at, but I don't think that is quite what is under discussion here.
My first thought is that God is apprehended through faith, not ratiocination. Aquinas noted that no one knows what God is, only what he is not. So faith is a kind of cosmic hunch making one, as John Henry Newman put it, "capable of bearing doubt." Whatever God is, He is not the terminus ad quem of a reasoning process. And the practice of one's faith often provides strange and strangely persuasive assurances from time to time. These are very difficult to communicate to others. But then, they are not meant for others. Experience trumps all theories. My experience and my take on that experience – my understanding of it – do not depend on the approval of anyone else.