Yeah, Tolkien's work is like that, he does borrow from Earth mythology but then he uses that to create the mythology of a different world. That's another reason I like the 'Dune' novels, which don't just rely on science fiction but have a strong religious/mythological aspect to them.

I guess I like making things up as much as anyone, but there is such a wealth of material in world mythology that it's just not easy to come up with something truly original (in fact, I don't think it can be done), and I enjoy drawing from these stories in many levels and degrees.