There are many words in the English language that have over time assumed an interchangeable role despite the fact they are different. One reason for this loss of definition is that the words may describe similar basic ideas, but with subtle yet important differences which for the majority of conversation and use are unimportant, and are therefore ignored. If the new ambiguity in the terms adds to their ease of understanding (or, rather, misunderstanding), the errant memes spread quickly through a population, and soon become the norm. One such set of oft misunderstood words are atheist and agnostic, which both describe the ideology of an individual who does not believe in God, but differ in the reasoning for their belief.

The word �atheism� is derived from the Greek prefix �a,� which means �without� or �not,� and the Greek word �theos,� which means god. The term atheist means one who denies the existence of a God, Gods, or any supreme intelligence. [1] An atheist believes that, using logic and reason, it is possible to prove that God cannot exist. Many atheists feel that �the idea of God as presented by the major religions is essentially self-contradictory, and that it is logically impossible that such a god could exist.� [2] While some atheists concede that proving the non-existence of all gods may be impossible, proving the non-existence of the god (or gods) held true by major religions is something not only possible, but logical. Still other atheists, often called �Strong Atheists,� insist that it is possible to disprove the existence of a supreme being of any kind. [3] Some arguments that atheists employ include Occam�s Razor, The Problem of Evil, The Freewill Argument, and the Incompatible Properties Argument. [4] The roots of this ideology extend nearly as far back as some of the most primitive theistic beliefs.

The earliest skeptical analysis of theism appears, ironically, in the Rig-Vega (~ 1000 BCE); a collection of hymns describing the mythology of the Hindu gods. [5] While the Rig-Vega hymnals are not strictly atheistic, they are certainly a precursor to the more reasoned arguments posed by an individual often considered the first true atheist, Epicurus (341-270 BCE). Epicurus �was a materialist and probably the first philosopher to develop the argument ([atheism]) from evil,� which basically highlights the logically fallacies inherent in the idea of an omnipotent, yet benevolent God in a world of suffering and evil. [6] True atheistic ideology lay fairly dormant for more than 1000 years after Epicurus, or at least there is little record of popular atheistic thinkers between the time of Epicurus and the Age of Enlightenment. Instead, those with differing beliefs, such as the early Christians around 150 CE, were called atheists, which helped to dilute the term into meaning anybody who doesn�t believe in the existence of the most widely accepted God. During the Age of Enlightenment, however, many popular thinkers professed atheistic leanings and ideas, including Rene Descartes, Julien Offray De LaMettrie, and John Toland. [7] Today, as much as 14% of the world population considers themselves to be atheist. [8]

Agnostics, like atheists, typically do not believe in the existence of a God, Gods, or any supreme intelligence. Unlike atheists, however, they do not think it is possible to disprove the existence of God logically or empirically. The word agnostic comes from (again) the Greek prefix �a,� and the Greek word �gnosis,� meaning knowledge, [9] and therefore the word itself does not necessarily convey belief or disbelief in God, but all modern definitions are used in the context of God and religion. Bertrand Russell, the famous philosopher, describes an agnostic as one who �thinks it impossible to know the truth in matters such as God and the future life with which Christianity and other religions are concerned. Or, if not impossible, at least impossible at the present time.� [10] Most individuals who subscribe to agnosticism do so because they see no compelling evidence of the existence of any supreme being, but as Carl Sagan (who is also often described as agnostic) once said, �absence of evidence is not evidence of absence,� so they cannot out rightly discount God�s existence.

While atheism and agnosticism share a common heritage in any kind of skeptical religious thinking, including that in the Rig-Vega (which is far more agnostic than atheist), the first true agnostic is also the individual who coined the term in 1869: Thomas H. Huxley. [11] Apparently, �Huxley originally meant this term as somewhat of a joke,� a kind of mockery against those who believed that they knew the absolute and immutable truth. Huxley used the Gnostics, a religious sect similar to Paganism in many ways, as a good example of a group of people who insisted they possessed the unconditional truth without any evidence or justification. Indeed, Huxley�s original intent was more to condemn any school of thought that arrived at conclusions or declarations of knowledge without any basis in reason, logic, or science, not simply thought directed at the existence of God or Gods. [12] Huxley�s sharp criticism of unfalsifiable (and therefore unscientific) ideas is well known through his staunch support of Darwin and Darwin�s theory of Evolution through Natural Selection, which eventually led to him being nicknamed �Darwin�s Bulldog.�

Obviously, it is easy to see why atheism and agnosticism are often used interchangeably. They share similar historical roots, use very similar methodology to justify their ideologies, and both have the same final conclusion; the belief in God is illogical and irrational. Equally obviously, atheism and agnosticism differ a great deal in the reasons for their equivalent conclusions, with atheists seeing the idea of God itself as a logical impossibility, and agnostics seeing the idea of God as one that is either not supported by the evidence, or impossible to verify or falsify.