Atheist groups (aka organized atheism) exist for the purpose of counteracting some of the more inaccurate and harmful ideas promoted by some religions. They are most concentrated in the United States, where speech criticizing religion has been under attack politically and in the media.
Atheism is, almost by definition, not an organization; its defining characteristic – lack of belief in any God or gods – rests on a principle of questioning dogmatism and authority. Until the early 2000s, groups organized in support of atheism were relatively rare. The presence of religion in the public sphere experienced a sharp upturn during the Bush-Cheney administration, partly due to Bush's self-promotion as a Christian who would "bring God back to the White House", and many atheism support groups began springing up in response.
- /list: list of atheist organizations
Differences from Organized Religion
It is erroneous to speak of atheism as a centralized group, much less a religion.
Although there are national atheist groups with local chapters, these are not officially representative of "atheism" in the same way that e.g. Catholic bishops officially represent the Catholic Church – there is no official organization which defines the beliefs and membership of "atheism" the way the Catholic Church can confirm or excommunicate its members into or out of Catholicism, whose definition is also completely controlled by the Church's central authority. "Atheism" is an expression of a principle which rejects the very idea of dogma and tends to be very leery of doctrine.
Atheism is a simple idea, a word meaning "no god(s)", and individuals who agree that the number of gods in the universe is (probably) zero may decide for themselves whether or not they are "atheists".
Indeed, it is almost exactly the opposite of a religion, except that there is nothing in the idea of atheism which would prevent an atheist from attending a church saying prayers, observing rituals, or displaying any of the other countless hallmarks of religion. An atheist simply wouldn't take the words as literal truth, wherever those words presumed the existence of a deity. Atheism corresponds to religious belief in much the same way that anarchism does to government.