@Ser: I am operating under the assumption that the terms "spiritual" and "religious" can be used interchangeably. However, if by religion you specifically meant organized religion, then there is a clear difference, and religion would then be a subset of spirituality.

I am familiar with that theory of Plato's. I briefly studied Plato in a course on the history of psychology. That theory is not too dissimilar to Freud's id, ego, and superego which came a long while after! Neither really have scientific support though.

And I guess that's all I meant to say. I don't see the purpose in studying the metaphysical because you have no facts and no evidence and all you can do is guess and speculate.

@Tam: Hm, those classifications are interesting. I think I would consider myself a materialist; the "mind" or "soul" is really only an illusory projection of a physical machine - the brain. Idealism is interesting though. Sounds a little bit like solipsism. And there is some truth to that. We generally trust what we sense, but how do we know that our senses aren't deceiving us? One of the only things I could agree with from Descartes' dualism was his realization that the only thing he could be absolutely certain of was his own existence. "I think, therefore I am."