Definitions of "atheism" used in debate
There are active and passive senses in which the term "atheism" can be used - because of the nature of the term the active sense is the original and by far the most common. However, in debate the sense in which atheism is defined may shift from "the active denial of the existence of God", to merely "the passive lack of belief in the existence of God". This can be seen as an attempt to shift the burden of proof from the atheist to disprove the existence of God, on to the theist to prove the existence of God. Recently a number of atheists have attempted to redefine the meaning of atheism as a lack of belief in the existence of God because they wish to shift the burden of proof in regards to the question of the existence of God. 
These active and passive senses are logically equivalent because they both equate to "God exists = False", but they are pragmatically distinct, because denying the existence of X, and X being amongst the things one has never considered the existence of, are different psychological states. The argument for them being different psychological states is that if "X being amongst the things one has never considered the existence of" were psychologically equivalent to the denial of the existence of X, then one would have to hold an infinite number of beliefs in the non-existence of all logically possible Xs, but since the human mind is finite, this cannot be the case.
Nevertheless, this distinction is a rhetorical device only, and does not succeed in shifting any burden of proof. This is because not only is the issue of burden of proof still, strictly-speaking, independent of the issue of the sense in which the term "atheism" is used, but it is impossible even to identify oneself as an atheist in the passive sense described above. Once one has considered the question of the existence of God (which one must do in order to describe oneself as an atheist), to be an atheist one must actively deny the existence of God. This is because, presuming agreement on the definition of God, a so-called passive atheist would be unable to describe the following sentence as either true or false: "God exists." To answer "True" is theism, to answer "False" is active atheism, and to answer "Neither" is not atheism at all, but agnosticism, and the option of ignoring the question is lost by entering the debate at all.
Atheists typically hold that no religious text can be our only source of morality, although they may contain useful ideas or principles. As atheists do not believe in any form of deity, books purported to be based upon the revealed words of such deities are not considered to have any more inherent moral authority than books written by people. For instance, it may be claimed that events in the Bible itself even encourage immoral behavior, such as the Israelite expulsion of heathen nations from Canaan, the stoning to death of homosexuals, poor treatment of women, and the institution of slavery. Christian apologetists claim, however, that these objections to the goodness of God are invalid.    
Despite their disbelief in God, many atheists live their lives to a high ethical standard as evidenced by a divorce rate among atheists that is much lower than that of Christians or Jews. 
Christian View of Origins
It is difficult to trace the origins of atheism as a result of the incomplete historic record. It is known that ancient Greece produced a theory of materialism as early as the 5th century BC. Materialism is a philosophical position that the material is all that exists. Therefore, it automatically excludes immaterial beings. In addition to materialism the Greeks also considered Spiritualism, in which the material world is an illusion and only spirit exists, as well as dualism, in which both the material and the spiritual exist (e.g. Christianity). It is important to note that while many atheists are strict materialists, some are not. As an example, some philosophical systems generally regarded as religions (i.e. Buddhism) lack deities and thus could be regarded as "atheistic faiths."
The writer of the Book of Psalms knew of atheists and atheism and registered disapproval in Psalm 14: "The Fool hath said in his heart, There is no God." The book of Psalms precedes the 5th century BC by hundreds of years[Citation Needed].
In the Great Britain 2001 census, 15.5% of the population identify themselves as having no religious beliefs 2001 Census. This category included agnostics, atheists, heathens and those who wrote Jedi Knight. However other articles suggest a much higher rate of around 52% in the UK once agnostics have been considered.
More specific research on atheists conducted in 2006 suggests that the true proportion of Atheists is 4% in the United States, 17% in Great Britain and 32% in France. The Christian research organization, the Barna Group, reports that 12% of Americans are atheist or agnostic. Given that the methodology of the Barna Group study does not distinguish between atheists and agnostics, it is impossible to say if their results support, or contradict, the 4% figure. Estimates of the prevalence in atheism in the United States are, however, almost always much lower than comparable estimates from Europe.
It is important to keep in mind that surveys containing an option for "no religion" are not necessarily identifying solely atheists. Indeed, many individuals may believe strongly in some form of god but not subscribe to any one particular religion, and as a result will enter a response of "no religion" on surveys. As an example, 14.39% of the respondents to the 2004 General Social Survey in the United States claim to have "no religion." Of a subsample (197 respondents) of those persons with no religion who answered a second question on the origins of man, 19.80% believe that God created man while an additional 43.15% believe that God created man by guiding evolution over time. Thus, cumulatively 62.95% of those with "no religion" still believe that God was directly responsible for the creation of man in some fashion. Clearly, then, many of those claiming to have "no religion" are not atheists. These data are available and can be analyzed online GSS Data Online. Additionally, some atheists consider atheism to be a religion and will not respond that they have "no religion" on surveys, often preferring an "other" option. It is also important to take account that identification with a theistic religion does not necessarily imply a belief in God; For example a poll conducted in the United Kingdom in April 2006 indicated that 63% of Christians believed in a "God or higher spiritual force" and 14% did not.
Public Disapproval of Atheists in America
Research by Penny Edgell, Joseph Gerteis and Douglas Hartmann in the American Sociological Review indicates that most Americans would be more willing to vote for a homosexual or Muslim presidential candidate than an atheist. The same study indicates that 47.6% of Americans would disapprove of their child marrying an atheist. More recent Gallup polls confirm this finding and indicate that atheists are among the most disliked minorities in the United States. In addition, former President George H.W. Bush has previously stated that he does not believe atheists should be considered citizens of the United States.
Edgell, Gerteis & Hartmann 2006- Table 1 (Percentage of respondents answering affirmatively):
|This Group Does Not At All Agree with My Vision of American Society:||I Would Disapprove if My Child Wanted to Marry a Member of This Group:|
|Recent Immigrant||12.5%||Not Asked|
The Problem of Evil
One argument against belief in all-powerful entities ('gods') is the existence of evil. Philosopher and materialist Epicurus (341-270 BC), wrote:
- Is God willing to prevent evil, but not able? Then he is not omnipotent.
- Is he able, but not willing? Then he is malevolent.
- Is he both able and willing? Then whence cometh evil?
- Is he neither able nor willing? Then why call him God?
Theodicy is the branch of study in theology and philosophy that defends the goodness of God despite the existence of evil.  In traditional Christianity and Judaism the book of Job is used to explain the existence of evil.  In recent times Christian apologetists often cite Alvin Plantinga's free will defense in regards to the existence of evil.   The work of St. Augustine is also cited in regards to theodicy. 
The Problem of Origins
Arguments against atheism sometimes invoke the Problem of Origins. This problem can be simply stated as:
- All things that exist have causes.
- The universe exists.
- The universe must have a cause.
However, cause does not necessarily mean any form of intelligence or God like being. God, according to atheists is a superfluous addition and completely unnecessary for the explanation of the universe.
Theists often claim that God is the origin of the universe and, thus, that this Problem of Origins is evidence for the existence of God. Atheists use a variety of possible counters to this claim but the simplest is likely that invoking God as "first cause" simply removes the problem one step. So, if the problem of the origin of the universe is solved by attributing it to god, it simply raises the problem of the origin of God. If God can be uncaused then, atheists claim, so can the universe. However, creationists claim that the first law of thermodynamics and the second law of thermodyamics argues against an eternal universe.   
- 10 Myths and 10 Truths about Atheism
- Decline of Atheism -CreationWiki
- European Commission report on Social values, Science and Technology, includes info on Religious beliefs
- http://www.communicateresearch.com/poll.php?id=77 Communicate Research poll for Premier Radio and the Evangelical Alliance (April 2006)