It’s amazing how many tragic, flawed decisions are made with "God on our side". I was watching the movie 'Nicholas and Alexandra' and every time he made an awful decision he was certain that he had 'God on his side'.
I think that the idea of god is an extension of our monkey brain hardwiring to obey the alpha male. With our big brains we are broaden the concept into the more abstract idea of God. All powerful, all knowing, and all benevolent. Group and tribal cohesion has served the proliferation of the species well. That’s why evolutionarily it is in us.

For all the miraculous advances in science and philosophy, we still follow our monkey brains, just like the monkeys and even like bacteria.