It was a long period of study for me, but I did have one epiphany moment and, oddly, it was while watching "Conan the Barbarian" (the original one with Arnie).
It's the scene where Conan (barbarian) and a more civilised chap are talking about their gods. Conan says that his god Crom lives on a mountain, only respects strength etc. and the other god says his god is greater than Crom, his god is the everlasting sky and Crom lives under him.
It hit me that is exactly how the gods we are supposed to believe are real have developed. It's all about my god is better than your god. That's the driving force in the development of a deities characteristics. On top of a mountain > in the sky > above the sky for example. The gods have evolved to fill the needs of the people that believe in them.