Writers disagree how best to define and classify atheism, contesting what supernatural entities it applies to, whether it is an assertion in its own right or merely the absence of one, and whether it requires a conscious, explicit rejection. Atheism has been regarded as compatible with agnosticism, and has also been contrasted with it. A variety of categories have been used to distinguish the different forms of atheism.
Some of the ambiguity and controversy involved in defining atheism arises from difficulty in reaching a consensus for the definitions of words like deity and god. The plurality of wildly different conceptions of God and deities leads to differing ideas regarding atheism’s applicability. The ancient Romans accused Christians of being atheists for not worshiping the pagan deities. Gradually, this view fell into disfavor as theism came to be understood as encompassing belief in any divinity.
With respect to the range of phenomena being rejected, atheism may counter anything from the existence of a deity, to the existence of any spiritual, supernatural, or transcendental concepts, such as those of Buddhism, Hinduism, Jainism and Taoism.
Implicit vs. explicit
Definitions of atheism also vary in the degree of consideration a person must put to the idea of gods to be considered an atheist. Atheism has sometimes been defined to include the simple absence of belief that any deities exist. This broad definition would include newborns and other people who have not been exposed to theistic ideas. As far back as 1772, Baron d’Holbach said that “All children are born Atheists; they have no idea of God.” Similarly, George H. Smith (1979) suggested that: “The man who is unacquainted with theism is an atheist because he does not believe in a god.
This category would also include the child with the conceptual capacity to grasp the issues involved, but who is still unaware of those issues. The fact that this child does not believe in god qualifies him as an atheist.” Smith coined the term implicit atheism to refer to “the absence of theistic belief without a conscious rejection of it” and explicit atheism to refer to the more common definition of conscious disbelief. Ernest Nagel contradicts Smith’s definition of atheism as merely “absence of theism”, acknowledging only explicit atheism as true “atheism”.
Positive vs. negative
Philosophers such as Antony Flew and Michael Martin have contrasted positive (strong/hard) atheism with negative (weak/soft) atheism. Positive atheism is the explicit affirmation that gods do not exist. Negative atheism includes all other forms of non-theism. According to this categorization, anyone who is not a theist is either a negative or a positive atheist. The terms weak and strong are relatively recent, while the terms negative and positive atheism are of older origin, having been used (in slightly different ways) in the philosophical literature and in Catholic apologetics. Under this demarcation of atheism, most agnostics qualify as negative atheists.
While Martin, for example, asserts that agnosticism entails negative atheism, many agnostics see their view as distinct from atheism, which they may consider no more justified than theism or requiring an equal conviction. The assertion of unattainability of knowledge for or against the existence of gods is sometimes seen as indication that atheism requires a leap of faith.
Common atheist responses to this argument include that unproven religious propositions deserve as much disbelief as all other unproven propositions, and that the unprovability of a god’s existence does not imply equal probability of either possibility. Scottish philosopher J. J. C. Smart even argues that “sometimes a person who is really an atheist may describe herself, even passionately, as an agnostic because of unreasonable generalised philosophical skepticism which would preclude us from saying that we know anything whatever, except perhaps the truths of mathematics and formal logic.” Consequently, some atheist authors such as Richard Dawkins prefer distinguishing theist, agnostic and atheist positions along a spectrum of theistic probability—the likelihood that each assigns to the statement “God exists”.
Definition as impossible or impermanent
Before the 18th century, the existence of God was so universally accepted in the western world that even the possibility of true atheism was questioned. This is called theistic innatism—the notion that all people believe in God from birth; within this view was the connotation that atheists are simply in denial.
There is also a position claiming that atheists are quick to believe in God in times of crisis, that atheists make deathbed conversions, or that “there are no atheists in foxholes“. There have however been examples to the contrary, among them examples of literal “atheists in foxholes”.
In fact, “atheism” is a term that should not even exist. No one ever needs to identify himself as a “non-astrologer” or a “non-alchemist“. We do not have words for people who doubt that Elvis is still alive or that aliens have traversed the galaxy only to molest ranchers and their cattle. Atheism is nothing more than the noises reasonable people make in the presence of unjustified religious beliefs.