Wow, so there IS something you call material evidence that you use to discern the existence of "God" who is NOT a certain way. Just what is it about that evidence that is so concrete that you can adamantly declare that, though? You did use the phrase "in my mind", so I take from that you have formed an idea of what God is not. Well, maybe that is a start. We can only hope! :o)
Yes, that's called apophatic thinking.