Atheism is the condition of lacking theistic belief.
The term atheism (French athéisme, from athée, meaning atheist, from Greek 'Αθεος, atheos, meaning godless : a-, without; + Θεός, theos, meaning god; it has Indo-European Roots) is formed of the Greek prefix α- (a-), meaning "without" or "not," and the Greek-derived theism (from Θεϊσμός, theismos), meaning a belief in a god. The literal meaning of the term is therefore "lack of belief in a god."
Types of atheism
Some atheists  (http://www.infidels.org/news/atheism/intro.html)  (http://kenneth.moyle.com/aa/atheism1.htm) distinguish between two variants:
Critics of strong atheism contend that atheism requires faith due to a supposed impossibility of proving negatives; an assertion that there are no gods requires omniscience to be certain there are no gods in the universe. Strong atheists counter that for most mainstream concepts of gods this is a straw man fallacy, since strong atheism is based on a priori, rather than a posteriori arguments. Strong atheists consider it irrational to assert the existence of a god whose existence transcends human logic and/or the, albeit incomplete, laws of physics. Other strong atheists, who rely on evidential grounds, maintain the case for the nonexistence of gods is supported by more evidence than the case for the existence of gods, and that negatives are possible to prove.  (http://www.infidels.org/library/modern/jeff_lowder/ipnegep.html)  (http://www.infidels.org/library/modern/richard_carrier/theory.html)  (http://www.discord.org/~lippard/debiak.html)
Philosophy of atheism
Atheism does not prescribe a system of values, which is present in other categories of atheistic thought including, but not limited to, Secular Humanism, Universism, Rationalism, and Objectivist philosophy.
Most religions include a moral code (e.g., the Ten Commandments) and teach that morality derives from their deity or deities. Their followers, therefore, often believe that to fail to believe as they do is to be without morals—or even, in the absence of a protective religious belief, to be defenseless against the corrupting influence of agents of evil. Atheists deny charges of amorality and accept personal responsibility for determining the morality of behavior.
Atheistic organizations of certain worldviews, such as Secular Humanism, provide examples of atheistic moral codes. Atheists accept that enrollment in a religion is unnecessary for a values orientation. Francis Bacon explains: "Atheism leaves a man to sense, to philosophy, to natural piety, to laws, to reputation; all of which may be guides to an outward moral virtue, even if religion vanished; but religious superstition dismounts all these and erects an absolute monarchy in the minds of men."  (http://www.worldwideschool.org/library/books/phil/modernwesternphilosophy/FrancisBacon/chap17.html)
In Europe's Middle Ages and even up to the 18th century, atheism was regarded as immoral, often criminal; atheists could be sentenced to death by burning, especially in countries where the Inquisition was active. While Protestants and many others suffered from discrimination and persecution by the then dominant Roman Catholic Church, Calvin was also in favor of burning atheists and heretics  (http://www.christianchronicler.com/history1/reform_in_french_switzerland.html)  (http://www.shareholder.com/bid/news/20030603-110529.cfm).
In some cultures, promoting atheism has been criminalized, and even many western European countries such as Germany and Spain still have (rarely enforced) anti-blasphemy laws on the books. Those who hold theistic views often consider those without a belief in a deity to be immoral, amoral or untrustworthy—unfit as members of society. The scriptures of most religions contain denunciations of non-believers; see, for example, 2 Thessalonians 1:6-9 in the Christian Bible.
Every military buildup in the United States since World War II has been accompanied by frequent use of the saying "There are no atheists in foxholes", a statement contradicted by the experiences of many former soldiers. During the Cold War, the fact that the communist enemies of the United States were officially atheists ("Godless Communists (http://www3.niu.edu/univ_press/books/257-5.htm)") added to the view that atheists were unreliable and unpatriotic.
In the 1988 presidential campaign in the United States, then Republican presidential-candidate George H. W. Bush said "I don't know that atheists should be regarded as citizens, nor should they be regarded as patriotic. This is one nation under God."  (http://www.robsherman.com/information/liberalnews/2002/0303.htm) Similar statements were made during the controversy surrounding the inclusion of the phrase "under God" in the American Pledge of Allegiance, words which were added to the pledge early in the Cold War period.
In Communism, Marxism and the Cold War
Atheism has been the official stance of most communist countries, including the People's Republic of China and the former Soviet Union. Karl Marx, an atheist, wrote that religion is the "opiate of the masses," which is often interpreted to mean that it exists in order to blind people to the true state of affairs in a society, and thus make them more amenable to social control and exploitation. Others suggest that communism itself can be seen as religion.
In the Soviet Union and in the People's Republic of China, some churches that submitted to strict state control were tolerated. Because of the communists' goal to eradicate traditional religion as what they perceived to be an irrational belief system, powerful religious groups such as the Catholic Church were among the strongest enemies of communism since its very inception. See also China mounts 'atheist propaganda' drive in Tibet (http://www.tibet.ca/wtnarchive/1999/1/21_1.html). Communist doctrine aside, many dictatorships have regulated or forbidden religious groups which were viewed as possible centers of opposition against their totalitarian rule. On the other hand, western intelligence agencies have often cooperated with local religious groups in order to build up opposition in hostile countries (an extreme example being the training and funding of the radical fundamentalist Mujaheddin in Afghanistan by the CIA in the 1980s).
Atheism is more common in the secular countries of Western Europe and in former or present communist nations than in the United States, and more common among scientists, particularly natural scientists, than among the general population (see the relationship between religion and science).
Notwithstanding Cold War attitudes, atheists are legally protected from discrimination in the United States and they have been among the strongest advocates of the legal separation of church and state. American courts have regularly, if controversially, interpreted the constitutional requirement for separation of church and state as protecting the freedoms of non-believers, as well as prohibiting the establishment of any state religion. Atheists often sum up the legal situation with the phrase: "Freedom of religion also means freedom from religion."  (http://www.au.org/)
Notably, in the Board of Education of Kiryas Joel Village School District v. Grumet, Justice Souter ruled that "government should not prefer one religion to another, or religion to irreligion."  (http://supct.law.cornell.edu/supct/html/93-517.ZS.html) Since Everson v. Board of Education established that "Neither a state nor the Federal Government can... pass laws which aid one religion, aid all religions, or prefer one religion over another," which applies the Establishment Clause to the states as well as the federal government  (http://atheism.about.com/library/decisions/religion/bl_l_BoEEverson.htm), the several state constitutions that contain clauses saying things like "no person shall be discriminated against because of religion, provided he or she acknowledges the existence of a deity" would be apparently going against the Court. As they have not actually faced challenge, the question has not been conclusively decided.
The recent Newdow case, involving the phrase "under god" in the United States pledge of allegiance, was thrown out because Michael Newdow did not have prudential standing, and as such it has no current bearing on atheism today.
In early 2004, it was announced that atheism would be taught during religious education classes in Britain. (http://www.reuters.co.uk/newsPackageArticle.jhtml?type=topNews&storyID=458497§ion=news)  (http://observer.guardian.co.uk/politics/story/0,6903,1148578,00.html) A spokesman of the 'Qualifications and Curriculum Authority' stated the following about the decision: "There are many children in England who have no religious affiliation and their beliefs and ideas, whatever they are, should be taken very seriously." There is also considerable debate in the UK on the status of faith-based schools, which use religious, as well as academic, selection criteria  (http://www.iht.com/articles/47799.html).
Due to some societies strongly promoting atheism, and some strongly condemning it, atheism may both be overreported and underreported in different countries. There is a great deal of room for debate as to the accuracy of any method of measurement, as the opportunity for misreporting (intentional and otherwise) a belief system without an organized structure is high.
The following surveys are in chronological order, but as they are different studies with different methodologies it would be inaccurate to infer trends on the prevalence of atheism from them:
A 1995 survey  (http://www.zpub.com/un/pope/relig.html) attributed to the Encyclopedia Britannica indicates that non-religious are about 14.7% of the world's population, and atheists around 3.8%.
In the 2001 Australian Census  (http://www.abs.gov.au/Ausstats/abs@.nsf/0/9658217eba753c2cca256cae00053fa3?OpenDocument) 15.5% of respondents ticked 'no religion' and a further 11.7% either did not state their religion or were deemed to have described it inadequately (there was a popular campaign at the time to have people describe themselves as Jedi).
A 2002 survey by Adherents.com  (http://adherents.com/Religions_By_Adherents.html) estimates the number of "secular, non-religious, agnostics and atheists" as about 14%.
A 2004 survey by the BBC  (http://news.bbc.co.uk/1/hi/programmes/wtwtgod/3518375.stm) in 10 countries showed the proportion of "people who don't believe in God nor in a higher power" varying between 0% and 30%, with an average close to 10% in the countries surveyed. About 8% of the respondents stated specifically that they consider themselves atheists.
A 2004 survey by the CIA in the World Factbook  (http://cia.gov/cia/publications/factbook/geos/xx.html#People) estimates about 12.5% non-religious and about 2.4% for atheists.
According to motherjones.com, 52% of Americans claim they would not vote for a well-qualified atheist for president. (http://www.motherjones.com/news/exhibit/2004/09/09_200.html)
The word "atheism" has been used polemically to describe the position of someone who does not believe in one particular deity, even if they do believe in another. An example would be its use as an accusation of the pagan Romans against the early Christians, and vice versa. It was also used against Socrates. Polemical usages of this term as an ad hominem attack are not discussed within this article.
Atheistic religious organizations
Atheism is not synonymous with irreligion. There are religious belief systems, including much of Buddhism, Unitarian Universalism, and Universism, which do not require theistic belief. A number of atheistic "churches" have been established such as the Naturalistic Pantheists, Brianism, and the Fellowship of Reason.
Views of religions on atheism
Jewish views of atheism
All formulations of Jewish principles of faith require a belief in God. In theory, the rejection of this belief is heresy of the highest form. It should be noted that such views are mainly fundamentalist in origin; in practice, rabbis have generally considered the behaviour of a Jew to be the determining factor in whether or not one is considered an adherent of Judaism. It is commonly recognized that it is possible for a Jew to strictly practice Judaism as a faith, while at the same time being an agnostic or atheist, giving rise to the riddle: "Q: What do you call a Jew who doesn't believe in God? A: A Jew." It is also worth noting that Reconstructionism does not require any belief in a deity, and certain popular Reform prayer books offer services without mentions of God.
Rabbi Abraham Isaac Kook, first Chief Rabbi of the Jewish community in pre-state lsrael, held that atheists were not actually denying God; rather, they were denying one of man's many images of God. Since any man-made image of God can be considered an idol, Kook held that in practice one could consider atheists as helping true religion burn away false images of God, thus in the end serving the purpose of true monotheism.
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