*Pizzasgood gets that long-winded look in his fingers as they head menacingly toward the keyboard.....
Horribly mutilated 9-foot zombie-monster things don't strike me as the religious type...
You never know. A probably ancient dead guy who hangs out in a small cave and watches new dead people exit the world all day might well have turned mushy and philosophical. And why does being a mutilated or 9-foot tall have to do with it? (monster is subjective, and it's the death realm so zombie is irrelevant). I think sitting there with half your gut missing while other people enter in one piece could make someone either very violent or very sensitive. I feel sad for the big guy

The point I was trying to make before is that nobody really knows anything. Your whole world could be a drug-induced hallucination. You have no way of proving that aliens or the Men in Black haven't replaced your memory. Neither way can be proved. We can each insist on our versions of reality, but it doesn't accomplish anything. Personally, I don't believe the chair that I'm currently leaning back in is imaginary, but I don't know that 100%.
As for science, it is only an approximation. We actually don't know any of the real laws of nature, if there even are any. This is why I'm able to have science and religion co-exist in my reality. Just because science doesn't show proof that God exists doesn't mean he doesn't. Science always changes in attempts to approximate reality. Look at what Einstein did. Newton made a great attempt, but it breaks down if you go fast enough. Einstein tried to do a better approximation for high speeds. It isn't perfect either. It's like using a Reimann Sum with n=5, then going to n=10. It still won't get the whole curve. Thus, anything is possible. General perceived experience says that an eagle will not shoot out of my butt tomorrow, but there is no way to prove that.
Religion (to me) is the same thing. It's an approximation. You can look at it in various ways depending on what your personal beliefs are, but in general it is an attempt to explain the world. Even if you are a Christian, and you believe the words of the bible are absolute truth, it is still only an approximation. You can't fully describe God in text, only approximate him. (Actually, a textual description of anything is an approximation). It probably says as much somewhere, I don't remember.
Neither of these approximations fully explains anything. Remember the "why" question? If you do it enough to scientist or priests, you'll probably get a "I don't know, shut up already!"
So in short, you cannot say whether spirits exist or do not in "real" life, only what you take as the truth. You cannot efficiently argue your opinion to be more valid. You can say that the majority supports your opinion, and that is all.
Life meaning. Another subjective topic. It depends on what you think life is. You can believe we are here to be tested before being allowed to exist in God's court. You can believe we are here to make God smile. You can believe we are here to cultivate the planet. You can believe we are here as punishment. You can believe we are here because some alien biologist forgot us. You can believe we are here because a giant turtle farted near a match, starting a big bang and leading to the evolution of humans and our superior though distant cousin the iguana. You could even believe we are here because we are not over there.
Me, I think everybody's life has it's own purpose, which is what that person chooses it to be. I think it is not destined, though God may have a desire for you to use it one way, and may urge you towards it. A good general part is to be happy and spread happiness. And to be helpful. Most of all, to laugh. The greater part for mine, I haven't discovered yet. There may not be one. I'll probably stumble across it. I might make it to bring life to Mars (if there isn't already). I might make it to destroy Microsoft. Or I might make it to do the iguana a favor and exterminate our pitiful race

Nah.
I liked the bit about escaping natural selection. I never heard that take on it before. In a way we are still there though. If you have some horrible problem, you are less likely to pass it down unless it doesn't kick in until late in life. Notice I said "less likely", yes I know many people still do. But we have still basically taken evolution into our own hands. Technically, as part of nature, we are still following it. Just in a different way from the others.
A note to the zealous: I actually don't believe we evolved, though I'm far from solid on that. However, I am perfectly accepting of it as an approximation. Besides, just because the bible doesn't specify the inner-workings of God's mind doesn't mean he just plopped us down. Maybe he sort of ran an "evolution simulation" in his head to skip it, or maybe we actually did evolve half-way, then he skipped us ahead. Or maybe we did evolve completely, but God created the initial life. Regarding the bible, the men who wrote it obviously did not know all there is to know. They did their best at describing it. Maybe God simplified it for them, maybe they made it up. In the end, it makes no difference. I believe there is a force somehow semi-responsible for my being here, who occasionally helps me out subtly. I believe that I should strive to be "good", and that being good or bad have their consequences. The details are fun to try to sort out, but don't matter in the end. Not worth killing a person over different beliefs, unless those believes are so funky they involve the guy running around chasing two-year-olds with a riding lawnmower and a backpack full of granades. Although killing may not be the way to go, that's a whole nother discussion. But, I have to get up for Calc III tomorrow, so I'll skip that one

Back on topic, are possessions possible in the
Planeshift world? I don't know. There are several ways it could happen:
A: Jack's spirit could leave his body and enter Bob's. Jack's spirit could already have been separated for some reason (death? worse-than-death? funky spell destroyed body but preserved spirit? Spell removed spirit?).
B: A naturally bodiless spirit, as in a species of beast that simply has no body, possesses Bob.
C: Spell (Dark-way probably) bends Bob to will of Jack, without Jack's spirit going anywhere. Could simply control Bob's body, or it could influence Bob's mind, making him actually desire the things Jack wishes him to desire.
D: Jack makes a "copy" of his spirit that enters Bob.
E: Crazy parasite slug wraps around Bob's brain and takes over (sorry, couldn't resist...)
F: Bob is hypnotized
G: Bob is insane and only thinks he is being possessed. Could be a multiple-personality type thing.
Okay, time for me to shut up and sleep.

Feel free to applaud the soothing absence of text.