I believe that God is man's creation, but that it has escaped control by man and morphed into a phenomenon that has an existence and an impact on the world regardless of the literal truth of any one religion. An inversion of the Christian creation story, where God created man and then man got out of pocket. The realm of belief where gods could potentially exist is a place where empirical truth is sort of irrelevant, and what is useful holds more sway.
There's a scene in the Illuminatus trilogy that pretty well summarizes my beliefs regarding the supernatural. Spoilers ahoy, you've been warned. It's a rather ridiculous scene, the presumed protagonists Simon Moon and Hagbard Celine have just summoned the goddess Eris to help them do battle with a lake full of Nazi zombies. She emerges as a 50 foot tall bucket of whoop ass and just starts cleaning house. Simon looks at Hagbard and says something like "I could swear you told me that she was just a metaphor for the creative force in all of us" and Hagbard replies "That's what she is when that's what we need her to be. Today we need her to be a Nazi-punting giant."