Dualism
As many have pointed out, the West in its thinking, whether consciously or unconsciously, has inherited a generally dualistic picture of the world. The influences on this are most likely multifarious, but one has always been singled out: Plato. The West in a way is built upon two great traditions: Christianity and Greek Thought. Plato, generally thought to be the most important Greek thinker in history, as well as having influenced Christian thought from the very beginning, stands as a vital source for both of these traditions. Plato posited a world of eternal Forms, a world of the Good, the True, and the Beautiful, in contrast to the fleeting shadowlands of the sensible world (though the thrust of this idea was not wholly unique to Plato, it had its roots in such 5th century schools as the Eleatics and Pythagoreans). It was only the Forms, Plato said, that could be known. The truly virtuous life was thus constituted by contemplation of these eternal Ideas, and Plato's Socrates gloried at the prospect of returning to this Ideal Realm as he spoke to his students before his execution.
How does all this relate to the sort of language used to describe a world-view? It relates because, I believe, the West has inherited along with Plato's conceptual scheme a specific way of talking about the world. A way of talking that degrades "crude matter", and glorifies the "spiritual world". Of course, this is not meant to be an across-the-board description of contemporary western thought. It is meant to specifically describe the language still used in the more religious elements of our society.
Now, the first thing I want to touch on is the use of certain words meant to draw out particular emotions and senses in the hearer (what speech-act theorists call the "perlocutionary force" of a statement). Consider the statement "So we're just matter in motion?". The term "just" here functions, albeit subtly, to load the statement with a value-judgement. Why is it used? Upon examination, it can be seen that the word "just" is used to convey a sense of meaninglessness, lowliness, and unimportance. The fact that statements such as these are used with such force, however, is seldom questioned or examined. I put the question to you: Instead of "just matter", why not "glorious, wondrous, mysterious matter"? The point here is that the language used to describe material reality, from the traditional western-religious perspective, is intensely value-laden from the outset. Such language needs to be justified before discussions over materialism versus immaterialism can begin to make sense or be fruitful.
So how might what I'll now just refer to as the "immaterialist" justify such language? Presumably, the reason it's used is to convey the fact that matter is just the sort of things that is meaningless, lowly, and unimportant (at least unto itself). Spirit, by contrast, just is the sort of thing that can be meaningful, glorious, and important unto itself. But why is this assumed? I think it's because throughout most of western history, for various reasons, it was assumed that brute matter just wasn't the sort of thing capable of functioning to produce the "higher" elements of human experience (love, beauty, glory, moral sense, etc.). It seemed that those things, if they were to have any reality at all, must be grounded in some other realm (in the soul, the realm of the forms, or "heaven"). And this leads to my first conclusion: There is nothing intrinsic to either matter, or spirit, qua substance that makes it more or less meaningful. Rather, it is what each substance is thought to be capable of producing that makes the difference. Thus, we see the question is not so much about matter versus spirit per se, but rather it is a question about function, and which substance can function in such a way as to produce such things as meaning, morality, or love.
Materialism
Because of the aforementioned assumptions concerning the apparent meaninglessness and etc. of matter, materialism is typically thought to be a sort of depressing world-view, full of despair and pointlessness. This is only partially true, however. Another reason for the apparent despair associated with a materialistic world-view has less to do with matter itself, and has more to do with the loss of God. When you cease to believe that an all-good God is looking out for you and has eternity waiting for you on the other side, it is understandably a despair-inducing situation. So I'm not claiming that the association of materialism with a certain level of despair is completely unwarranted, but I am claiming that any despair resulting from the world-view is only relative to the loss of a benevolent care-taker, rather than having to do with matter itself. The emphasis, however, does tend to be on the unimportance of the material world itself, hence why a Christian will typically assign the property of "being more hopeful" to other spirit-adhering religions even if they lack the idea of an all-good God (such as certain forms of Buddhism).
Let's turn again, then, to the question of function. If the issue really, in part, pertains to what sort of substance could function to produce "higher things", then I think the assumption that only spirit can has been taking on water for several centuries. Ever since the scientific revolution and the Enlightenment, both philosophy and science have made great strides in explaining just how such things as morality, beauty, love, and meaning can be firmly grounded in the physical world. Put another way, we have for the most part discovered that material reality is capable of functioning to produce what we call "meaning", "morality", and all the rest. The vast majority of ethicists now see how morality can exist without God (including many Christians, such as Oxford's Richard Swinburne). Similarly, we have seen how such things as consciousness, love, complex ideas like "glory" and etc., can all be grounded in, if not made to be identical with, physical reality. If this is true, and I think it is (not that the issue's settled, but that we've made great strides), then the assumption that only the spirit-world could "matter" (no pun intended) appears bankrupt at worst, and in need of serious questioning at best. Language such as "just matter" and "just atoms" needs to be rigorously analyzed and turned against the users of such phrases. We can use our own value-laden language to say "What, do you mean the glorious matter that produces all the exuberant and beautiful species of Earth? That 'crude' matter out of which the Roman Colosseum was constructed? The 'atoms in the void' that got us to the moon in the spirit of exploration?".
The question of meaning, however, appears more complex. When people use the term "meaningless" to describe the universe, it's hard to see exactly what they mean (again, no pun intended). In what sense is a universe without a God less meaningful than a universe with one? Simple answers to the question don't seem as obvious when looked at closely. For example, one quick response might be "Because if God exists, then he has a plan for the universe". That may be true, but in a way it begs the question. Why should God's plan for the universe constitute it's "meaning"? Is meaning really just identical to a meta-narrative? Is it not possible that there be a meaningless meta-narrative? As a brief thought-experiment, assume that my consciousness has now become disembodied. Further, let's assume that I have attained a perfect knowledge of the universe, that I have attained perfect-power, and that I have nothing but good intentions for the world. Now consider: Does whatever I conceive in my mind as the universe's "goal", it's "purpose", become it's objective meaning? The question is important because in this thought-experiment I have become nearly identical with God. So then, why is it that God's purpose constitutes the universe's meaning and not mine? Someone may say, reasonably, that it's because God created the universe that he has the sole right to determine it's true meaning. That may be true as far as it goes, but it only leaves us with deeper questions: What is it about an act of creation that makes my intention for that entity it's objective meaning? After-all, human artifacts are constantly used for purposes other than those for which they were created, are those not legitimate "meanings", or uses, for the objects? These are not easy questions, and they take us to the most profound question in all of philosophy: What is meaning?
Religion as a Language
What follows, I think, from the preceding discussion is that part of religion's importance and vitality is as a language for talking about the world. Immaterialists can refer, in "high language", to the spiritual realm (or the spirit-imbued universe) as "glorious, wondrous, mysterious". I, with equal right and validity, can refer to a Godless universe as "glorious, wondrous, mysterious". Part of what gives our world meaning is the way in which we choose to talk about it, and hence the way in which we choose to think about it. Using words like love, wonder, and majesty more fully capture, in a beautiful way, some of the very complex aspects of human experience. Religion is vital because it has it's own narrative with it's own language to tell the shared story of the reality of homo homo sapiens, somewhere on a rock lost in the universe. It has its own rituals and rites, which themselves are a kind of language, in order to more fully tell that story. I myself am not religious, but to lose religion would not be to lose some "archaic mythology", but to lose part of what it means to be human: Telling stories in a language all our own, conceiving of things in a space that transcends our historical context, and giving our lives a direction that it may lack without such narratives. All of these issues require further thought, further analysis and exploration, and I hope what I have said serves to stimulate some of that.