So says Professor Bainbridge:
[Cruise] forgot to mention that a science fiction writer invented Tom's own religion, in whose belief system an alien named Xenu figures prominently. Which may go a long way towards explaining both Tom's interest in science fiction and his inability to express that interest coherently.
Xenu is Scientology’s version of Satan. Satan is a supernatural being while Xenu was a dictator from another planet. Is one belief really any more silly than the other? I don’t see how.