to go with my earlier post, i think people throughout time have created the idea of gods, ghosts, aliens, etc as a way of trying to make sense of our existance.
The truth is probably that a puddle of ooze happened to have all of the exact requirements to build us and when we die, that's it. game over. no purpose of life, no higher power or greater meaning. just born, live, die, the end.
it really makes us so much more insignificant when you think about it that way.