Xenu was only the galactic overlord, not a God at all. He wasn't even magic at all, he was simply the one responsible for sending rockets to Earth that were loaded with nuclear bombs. The rockets were targeted to land in volcanos. When they got there, they blew up, littering our world with frightened thetans (souls) of the people that were on the rockets. It was a plan to decrease surplus population on some of the planets that Xenu controled.
Rhizo
Rhizo