Quick note to theocrat, and others, before I begin: There's enough room in the movement for Christians, Athiests, Agnostics, those of other religions, etc. I don't understand the motivation to try to convince people that "if you were a REAL supporter of liberty you would also agree with me on xyz". I also don't know what the point of trying to prove one's intellectual heritage to be supperior is, but I don't think it accomplishes anything good.
Now:
Yes, i am a materialist. I don't see how one could be anything else without making assumptions a priori. So, we know nothing about reality, but we have senses thru witch we can observe. We can think, and we can sense. We notice that these senses are connected to our thought. We start to see patterns.. we form assumptions about these observations. We are able to predict them (when we think, we can raise an arm and hit a wall, which hurts). We call what we can sense, reality. The assumptions that don't fit with what we observe, we modify until they fit. The assumptions we hold about reality, might not be the true reality. But at least they are a ever closer approximation. We have no other way of observing reality than our senses. We can make reasonable assumptions of nothing but the world that we can observe. We know that these assumptions are reasonable because we can test them against reality.
Of course, anything sensed through the five senses must be material in nature, since our senses are mechanisms that respond to physical stimuli. I submit that the human mind is not purely material, however.
I think it's actually fairly self-evident, but I'll briefly offer a couple examples of arguments for the non-materiality of human consciousness:
In theory, any purely mechanical or natural thing can be observed, and its existance proven, even if we are not capable of it now. Any such system is completely determined by the position and nature of its particles, because that is all there is. Consciousness is different, because it is by definition impossible to observe, or define based on the position of particles. Suppose one completely duplicated you, exactly replicated the position and nature of every particle in your body. It would be impossible to know for sure whether that being experienced self-awareness or not, despite having full knowledge of its physical nature. It's behavior would be indistiguishable from yours in a mechanical universe -- completely determined by the position and nature of its particles (until differing environments changed you and it, of course). If such a charictaristic exists, which cannot be determined despite perfect physical knowledge, that charictaristic cannot possibly be physical.
Along another line, in order to concieve of something it must either exist or be an extrapolation or conglomeration of things that do exist. There is no possibility, from a naturalistic perspective, of a truely original idea. Try to imagine a fifth dimension. We've got four dimensions to work off of, and it's still impossible. Where is the naturalistic source of value statements about things, statements about meaning, purpose, goodness, beauty, etc? We're hungry, we want food. We're thirsty, we want drink. We'd like to detect dark matter, in order to further our scientific understanding, thereby ensuring the species' survival, we'll use Einstein's gravitational lens effect. This is the extent of the human mind according to the naturalistic model. The fact that some now wish to banish those pesky value judgements from the human consciousness, and conform ourselves to the naturalistic model, does not remove the inconvenient detail that those things shouldn't really have ever been here in the first place.
If one does accept the premise that the human consciousness is indeed not purely mechanical, than the first place one would look for interaction with the non-material would be in the consciousness -- I submit that this is exactly what we find. Thus, our five senses can observe physical reality, while the metaphysical interacts with the conscousness (and perhaps, if one believes in such things, occasionally messes directly with nature as well, in a non-repeatable manner).
Now there may be more to reality than we can observe today. We may need better instruments to observe these (like those small particles that make up the atom). But the bottom line is, that everything that effects us, is also observable to us. Metaphysics says that there are things that effect us that can not be observed . I think this is a contradiction. Even if the methaphysical thing is itself unobservable, the fact that it can reach out and touch reality means we can see and observe the effects it sets into motion. That simple fact means that its can be observed and it is not methaphysical, its just hard to observe. We can form assumptions about when and how these motions start.
Like a stone falling into water, even if we did not see the stone wee will see the rings in the water, and we can make a reasonable assumptions that it was caused by something falling into the water. (If we live below the surface as a fish or something.. we can start to make reasonable assumptions about there being something above the surface..)
QM (with chaos theory) makes backing out physical causality in a deterministic fashion theoretically impossible for systems too sensitive or causal chains going too far into the past. This is just an example of an idea, but one way the consciousness could affect the physical state of the brain is by manipulating the wavefunctions of particles in neurons.
If something invisible keeps giving us a electric shock every now and again, we try and predict when it happens. Maybe it happens every time we think something bad. We would then make a reasonable assumption that someone can hear what we think, and that it does not like us being bad. We could make all kinds of observations and predictions about this being by observing when it chooses to interact with reality. But what if its behavior was not predictable, what if those shocks where completely random? Well then nothing we did would make a difference, and the theory that, a being caused all those shocks would be unreasonable, because the theory would not help us predict reality.
A methaphysical being that sometimes interacts with reality, can be observed thru the consequences of these acts. We can use logics to make predictions about when these acts occur. If the being is not logical, then it is random. a methaphysical being that is random, is really no different from a randomness itself. There is no reason to assume that randomness has any properties, that randomness is a being that can think etc.
I don't think this is true at all. If one experienced electro-shocks every time one lied, the physical source of those shocks would be investigated -- in the mean time theories would be proffered about the mental state of a liar causing the shocks in some way, etc. Finally, if the source was totally unexplained, it would be marked up to the "lying electroshock force" -- the last thing that would happen is that we would assume a non-physical being. The fact is, no physical evidence could really prove the non-physical -- which, as I pointed out, makes the complaint that "no physical repeatable evidence exists" for God rather empty, since evidence meeting these criteria is not possible even in theory (nor is evidence against possible). The evidence for God, if it exists, would be found in the human mind -- more specifically, one's own mental nature.
Of course, if one is not really looking for rigerous proof but merely evidence, and one is not resistant to the idea of the non-physical, some physical observations may be convincing. E.G, excellence of nature -- but such observations will always be explainable to those seeking a purely physical interpretation if at all possible.
So coming back to it.. we can have different definitions on reality. But the only one that seems reasonable is, reality is everything that affects us. Everything that affects us can be observed. Everything that can be observed, can be made predictable. Only things that do not exist, or things that are random can not be predicted.
Broadening the definition of reality to include things that can not affect us.. is pointless. There is no reason to speculate about thinks that don't matter one way or the other. A powerless god is no god at all. A random god is no god at all.
(Oh.. almost forgot, quantum mechanics can be proven and predicted. Its part of reality. There is after all a theory that is testable against reality. As I understand it the weird part about it, is that observing the state of the thing, changes the state of the thing. They have still managed to find a way to test this in a lab, and put it to practical use.)
Cheers
Certainly reality must affect us, and be observable. The question is, should we restrict ourselves to observations that are repeatable, communicable, and come through our five senses, or is one willing to admit evidence related to the nature of one's own mind? It seems to me that we do observe our own mental nature, and state, as well as observing through our senses. For example, according to the senses, humankind could be nothing but automata emulating intelligent behavior -- it is only by the observation of one's own mind that one realizes that is not the case.
And, QM may be understood to some extent, and is certainly observable, but it is fundamentally different in that it is not deterministic. The position and velocity of particles is actually in an undetermined state until observation -- no deterministic rule dictates in what state they will be under observation. This is not a lack of knowledge, but an actual element of randomness.
I didn't touch on this much, but I think we must also consider the definition of physical vs. non-physical. Science never truely explains anything -- it merely recognizes patters, and tries to reduce the number of unexplained phenomena by attributing as large a number of observed behaviors to as few phenomena as possible. Thus, we have a large number of behaviors attributed to "gravity", "electromagnitism", "weak or strong atomic force" etc, but none of these are truely explained. We seek a grand unified theory, so we will have only one unexplained force, but still that force will remain unexplained. Why do we not consider that force "supernatural"? Is the question only one of repeatability? A phenomenon which always occurs is natural, while one which does not always occur is not natural? We have a clearly defined area of unpredictability in QM, perhaps then certain behaviors of subatomic particles are "supernatural"? Or, perhaps we should include randomness in the physical, and reserve only non-random, non deterministic effects to the spiritual. The only non-random, non-deterministic decision making that I can think of is a mind.
So, are we really reduced to the idea that naturalism means there is no such thing as a "mind" in the real sense of the word, that can make real decisions, but only randomness and determinism exists? And conversely, a belief in the nonphysical means a belief in mind? If so, on what basis do we exclude the idea of mind, when we so clearly observe an example of it in our own consciousness? Why is that the odd man out, so to speak, in the pantheon of naturalism?
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. Check out the quantum eraser experiment for an idea, for example, at: 
