The term atheism is derived from the Greek prefix a (meaning "without" or "not") and the Greek theos meaning god, giving the literal definition of atheism as someone who is without a god. There are various ways of using the term. It may mean lack of belief in gods (weak atheism) or belief in non-existence of gods (strong atheism).
As understood within the philosophical tradition, "atheism" means belief that God does not exist, and thus the view is contrasted with both theism (the belief that one or more gods exist) and with agnosticism (the belief that it is impossible to know for sure whether or not God exists). Atheists, agnostics, and positivists (who believe that "God"-talk is nonsense) can generally be described as nonbelievers. Philosophers, in introducing the philosophy of religion, often point out that it is important to distinguish between these two statements: "I do not believe that God exists" and "I believe that God does not exist." The first claim is consistent with both agnosticism and atheism; the second is consistent only with strong atheism.
However, the above definition of atheism does not distinguish between strong and weak atheism, which is commonly drawn within the freethinking tradition (as distinguished from the philosophical tradition).
Furthermore, an atheist can be both a strong atheist with respect to the Judeo-Christian God and a weak atheist with respect to any other gods.
It is estimated that about 2.5% of the world's population classify themselves as atheist, and that about 12.8% classify themselves as nonreligious (according to the Encyclopaedia Britannica). These percentages are generally higher in European and (formerly) communist countries, and lower in the United States and developing countries.
See the rationality of atheism for further discussion.
Many atheists are generally misunderstood in many societies, and if they openly express their non-theistic points of view they may be mistreated, ostracized, or subject to discrimination. For example, even in the officially-secular United States, George Bush said during his 1988 presidental campaign [1], "No, I don't know that atheists should be considered as citizens, nor should they be considered patriots. This is one nation under God." Like their religious counterparts, many atheists align themselves with organizations that express or support a non-theistic worldview.
Stub: In Europe's Middle Ages, atheism was regarded as immoral, sometimes even criminal.
Please feel free to contribute to the history of atheism, or any other part of this entry.
--- See also: secularism, rationalism, philosophy of religion, the rationality of atheism, listing of noted atheists, agnosticism, naturalism, theism, deism