The subtle? What is the subtle? I have never seen a spirt or specter or astral projection. But WHY can't they be physical things? This topic is all about the why.
And who said anything about ruling out the spiritual? What IS the spiritual? How are you defining it?
Do you believe in vampires? Why not?
And please don't make this an "us against them" thing. Don't group people together into spiritualistic people and non-spiritualistic. Even spiritualistic people have different definitions. I know many that don't believe in astral projection or ghosts or anything of the sort. And I don't share the views of all other non-spiritualists either. Heck I don't even know if I'm not a spiritualistic person. I need to know what it is first.
EDIT: And one very important thing to understand is ...you ask me how I explain astral projection. I don't. In the same way someone who didn't believe lightning was a sign of the gods being angry at us, didn't know how to explain how to his friends who happened to believe it WAS something done by the gods. The difference is that his friends led their lives believing something which isn't true, while he didn't.
But more importantly, when you have spiritual beliefs, what makes you choose one view VS the other? What is the criteria you use to choose between christian beliefs and buddhist beliefs? Or to say both of them are wrong? What makes you pic one of the thousands of different views on spiritualism, is what I'm asking?
Ok, when I was typing this out I was not literally talking about you...I often do this when explaining things without clarifying first. Sorry...I did not mean to be an ass about it if I sounded that way.
But to answer your questions...
These things are not physical because they are mental. They are all about the mind, perception, and consciousness, which we all know are intangible. Everything cannot be physical. If that were so we would not know what physical is… a rudimentary comparison to this is like saying we would not have light without darkness. Remember though, nothing is black and white…of course there are infinite shades of grey that helps us refine our understanding of the world.
You are right, not everyone believes the same things or experiences the same things. Everyone's experience is unique and different people need different things to develop spiritually.
Some of the links I posted are one place to start when talking about "the subtle"... This is the realm of thought energy primarily, I think. There is a Hermetic axiom : "The ALL is MIND, the UNIVERSE is MENTAL." For me, spirituality deals with this. How we perceive things. How this plays into consciousness, unconsciousness, and super-consciousness (this would be achieved through meditating and other practices). Understanding the Mind. This is why Jung was so into the occult as a psychologist. Hermeticism is part of Western Esotericism. Many of these things link up with the East too. These axioms are the root of most spiritual beliefs.
I guess I am talking about mysticism then :
Mysticism - Wikipedia, the free encyclopedia
All major religions have a mystical branch (and these all have many axioms in common).
I also suggest the Tao Te Ching for insight into this.
It is hard for me to define clearly because the subject itself is so vast. I am sure there are people out there more capable than I am of explaining this better if my responses are not clear enough for you. There are probably a few on this forum too.
Theosophy is a good example of all religions trying to get to the same thing which is primarily what I am exploring right now…I was raised Catholic and still enjoy learning intellectual Christianity as well as other religions, mystic religions, and the occult/esoteric.
Theosophy - Wikipedia, the free encyclopedia
I think religious doctrine is actually important for some (I am NOT talking about religion in regards to anything else…we don't need to go
there right now). Some people need structure to reach God, or Oneness, or whatever you want to call it. People choose religion for many reasons ...cultural, preference of doctrine or beliefs, or just blindly choosing without thinking about it (all too common)
The realm of these things is vast. That is why people can spend their whole lives studying it like theologians and mystics.
This is wonderful and fun

: (I recommend you check out Alan Watts...atheists and theists alike can appreciate him)
[YOUTUBE="http://www.youtube.com/watch?v=BE5M8743a1s"]Alan Watts - Atheist Spirituality[/YOUTUBE]