I wrote this for my LJ, but cross-posting it here seems appropriate:
I self-identify as an Atheist.
But I don't like the word. Naturalist or Materialist would be better, but they've long since been claimed by other ideas. So Atheist it is.
Why don't I like the word? Because it is defined by negation - OMG? You, like, don't believe in god?. Yeah, I don't believe in god, I don't believe in fairies either, or unicorns, or spirits or ghosts or some mystical energy that, like, binds us together dude but that's not why I'm an Atheist. It's the other way round, I don't believe in those things because I'm an Atheist.
I'm Atheist because a world that is driven not by will, but by the quiet machinations of mindless material things driven not by purpose or intent but by the simple and repeated application of rules (in other words a natural world or a material world) not only appears to be what actually is out there in terms of what our senses and sciences can reveal to us but is a world more intellectually fulfilling and aesthetically pleasing.
There is, of course, much we don't understand and quite possibly will never understand - there is no real reason to suppose that the world is such that it can be understood by human minds, yet alone will be - but a naturalist view at least presents us with a world that is accessible. I believe consciousness is a product of the human brain; no brain = no consciousness. How it works I have no idea but it allows me to be very sure of certain things: you are conscious too, for example. It means we can, in principle at least, take a good shot at understanding why we are conscious, and whether our pets are conscious too; it means that we know already about brains and minds actually makes sense.
In our naturalistic world, we choose our own path; make decisions about what is meaningful or desirable for ourselves, and use the information we can gather about the world to make the best decisions we can knowing full well that this is it; our one shot at life and that the only criteria we can meaningful judge it on are the ones we choose for ourselves.
I choose Atheism not because I reject ideas of god, and the supernatural, but because I embrace the notion of a material world - one we can touch and feel and test.