Lost_In_The_Fog asked, "But what about the unseen spirit world generally such as poltergeists, jinns, voodoo, etc.(?)"
I am an atheist. I believe there is no "spirit realm" inhabited by any sort of being: No gods, no ghosts, no ghouls, no souls, no devils, demons, sprites or 7-Ups. Not even a Being Crosby.
So how do I explain "Strange phenomena"?
Well, first of all there is LYING. It seems many have never heard of this phenomena, but I assure you it is totally real. Here's how it works: a person says something happened that never did actually happen. There are people who make good livings by lying. One example of this is the clergy of any religion, followed by the "royal families" of any nation, followed by the people who sell and promote homeopathic "medicine." This list is not complete and could be much, much, much longer.
This is followed by misapprehension. It is funny, but while people will admit that there are SOME crazy people in the world, it never occurs to them that THEY might be one of the crazy people who ought not trust their limited and defective senses. They will tell you with absolute sincerity that "they know what they saw"or heard or tasted or felt. They are the 100% accurate perceivers of absolute quantum reality and everyone else is wrong.
Yes, I get the irony here - you want me to examine myself, don't you?
I have been entertained by optical illusions, I have experienced auditory hallucinations, and I have seen things that might - or might not - have been there. I have had well-intentioned people predict my future and I have paid to have my horoscope drawn up. I have also dismissed ALL of this as meaningless "entertainment."
Why is it that when the dead speak they sound like lunatics who can barely remember their own name, let alone their favorite color? Bring me the ghost of J. P. Morgan - or even Nick Darvas - and let him give me some actionable information, and I'll consider becoming a believer, but until the it is just J.Z. Knight hawking her idiot alter ego Ramtha-Lama-Ding-Dong!
But you know what? If YOU want to believe this crap and give your money to fake Xtian fakirs, magic soofis, healing monk-eys, or psychic detectives on a cacye from the flying spaghetti monster himself, knock yourself out! I couldn't care less - UNLESS your ghost tells you to cause harm to another person, in which case I will be at your door with a pitchfork in one hand and a torch in the other and a shotgun in the other. Fair enough?