As far as the spirit realm goes, there are a LOT of unexplained mysteries in the history of the earth. But just because it's unexplained doesn't mean that we can just attach an explanation to it to make us feel better. The thing I don't like about the "Spirit Realm" explanation of things is it ends there. Spirits are supposedly on a different plane of existance than us and therefore are not really studiable. I am for finding out the real scientific reasons for things more than slapping "demons" or "angels" on the unexplained.

Another thing is we don't understand our brain a whole lot yet, but we are getting there. If you think about what the brain is capable of doing it can give a window into the explanations of a lot of the paranormal stuff. The fact that we can halucinate is a big one for me. If someone takes some Acid their brian can conjure up some wild halucinations and all that is needed is an unstable brain, nothing else.