This has sparked a great discussion.
Religion is belief system (it matters not what specific religion), based on the the acknowledgement that there exists something greater than the individual human mind. Individual religions incorporate cultural systems, fables, and rituals designed to enforce that belief in a way that all members can comprehend even though it is accepted that they are by nature incapable of comprehensive religious knowledge (just as an ant in your kitchen is incapable of understanding your mind). Religion is typically the basis for society, because it establishes a world view and cultural rules that allow humans to share similar ethical and moral positions including but not limited to family, sexuality, law, and life itself. Basically, religion is the acceptance that we are all children of something greater.
Close, but a little off. It's not that society follows religion, but more the other way around, as a way to control the masses and explain the unknown.
Atheism is simply an individual choice NOT to adopt the belief that anything exists greater than the individual human mind or the collective human experience. It is an existential and purely materialistic, in that "if a thing cannot be proven through observation or scientific evidence, it does not exist." In atheism, belief is fluid, in that the atheists of the 1500s are very different than the atheists of today, because the science and understanding of the universe has changed. Atheists are free to define their own ethics and morality, and common moral positions, and are not bound to any cultural standard.
Wow, you really don't know what you are talking about. First of, it is not a choice, it's simply a matter of believing or not. Saying it's a choice is one of the most idiotic statements that can be made on the subject. Beyond that, it is simply the lack of belief in any supernatural deities. It does not require anything else. And yes, atheists of the 1500s are very different from the atheists of today, but guess what, so is every freakin one else. Oh, and in case you didn't notice, all groups are free to define their own ethics and morality, though they all are bound by cultural standards. The primary difference between atheists and theists in this respect is that theists pretend (well, most believe it, but belief does not make fact) that they have some holy scripture that they base theirs on, therefore making it better than everyone else's.
Personally I know many atheists. Spending a great deal of my youth in the Unitarian church, I watched many of my friends come to adopt a position of existential materialism as they grew up. Their lives tend to follow similar themes. Many are not happy that others would accept the concept of something greater than what experience or empirical evidence can show. This pushes them to evangelize (or educate as they call it) just as other religions do, and fosters the concept (as Heron mentioned) that they may indeed be a religion. It would be a struggle to be a real atheist, in that our wishes, hopes and dreams are based on a sense of spirit. I find that religion IS human nature. From the time we are children, until the day we die, it is necessary to have the faith that there is something more, something beyond what we can see, read, taste, touch, feel or smell. Our fantasies are our way of reaching for that. Otherwise life has little value beyond pleasure or pain, and the sensations from acquisition or loss of the material.
No offense Custosnox, but it is my experience that atheists have very sad lives filled with loss and tragedy, not because of any cosmic or supernatural karma, but because society provides very litte space for them.
and all of that is one of the biggest crock of shite that I've ever seen, and pushed by so many theists that it's truly sad. I am willing to bet that I know a great many more atheists than you, and on a large part, they tend to be a good deal happier than the theists that I know. (actually, I think there is a study on this out there as well, but just going from memory here and can't back it up) Of course the general public sees the ones that are outspoken, often truly pissed off about how they have been treated by others. These folks, and yes, I'm one of them, only make up a small portion of the community (and those who don't even associate with the community, though that does not keep them from being an atheist). I'm willing to bet that everyone in this forum actually knows several atheists and don't even know it. Oh, and the group that is trying to push everyone else into atheism fall into the category of atheism known also as anti-theism. These are the ones that think that religion is inherently toxic. No, I don't fall into this group. While I think we would be better off without all of these mythologies, I feel everyone should be allowed their beliefs (or lack there of), as long as these are not forced on others, and do not hurt others. However, because the angry and anti groups are generally the most vocal, these are the ones that most people think represent the vast majority of us.