We're going to be restricted to "dead" religions as Jim doesn't want to mess around with anything that important to anyone if he isn't intimately familiar with, so Hinduism is out.
Egyptian sounds good. Thoth is one I'd like to see. "He was the god of wisdom, writing, hieroglyphs, science, magic, art, judgment, and the dead." - Wikipedia. Any god of magic could be fun.
Greek, Norse, and Egyptian gods are the ones we usually see. Probably because we know more about them than most old religions.