An atheist is defined as anyone who is not a theist. The definition of atheist is thus anyone who does not happen to believe in the existence of any gods, no matter what the reason. This is a broad definition of atheist which describes the minimal position common to all atheists, no matter what else they may happen to believe or not believe.
Dictionaries sometimes define atheists more narrowly as the denying the existence of God or gods. This narrow definition is true of some atheists, but not necessarily all. There are no political, ideological, philosophical, or religious views which all atheists share.
The Oxford English Dictionary, Second Edition, offers the follow definitions that are relevant to correctly defining atheist:
a-, prefix: from Gr. ...pref. of privation or negation = without, not, -less, in words introd. into Eng. through L. and Fr. as abysm, adamant, amethyst; or through L. as acatalectic, adiaphorous, apetalous; or from Gr. direct (or through a mod. lang.) as amorphous, adipsy; or formed on Gr. elements, as abiogenetic, agnostic. In the latter case, a- has become a living prefix of negation = un-, non-, applied not only to words from Gr., as a-cotyledonous, a-chromatic, a-philanthropy, but also to technical words from L., as a-caulous, a-sexual.
theism: a. gen. Belief in a deity, or deities, as opposed to atheism. b. Belief in one god, as opposed to polytheism or pantheism; = monotheism. c. Belief in the existence of God, with denial of revelation: = deism. d. esp. Belief in one God as creator and supreme ruler of the universe, without denial of revelation: in this use distinguished from deism.
atheism: Disbelief in, or denial of, the existence of a God. Also, Disregard of duty to God, godlessness (practical atheism).
atheist: One who holds the doctrine of theism: in earlier use = deist; in later use, esp. as distinguished from this: see note s.v. deist.
disbelief: The action or an act of disbelieving; mental rejection of a statement or assertion; positive unbelief.
disbelieve: 3. intr. with in: Not to believe in; to have no faith in: cf. believe 1, 3.
believe: 1. To have confidence or faith in (a person), and consequently to rely upon, trust
Atheists may therefore deny the existence of some or all gods, and for varying reasons, but denying the existence of gods is not necessary for the definition of atheist.
"All children are atheists - They have no idea of God."
- Paul-Henri, baron d'Holbach
"I contend that we are both atheists. I just believe in one fewer god than you do. When you understand why you dismiss all the other possible gods, you will understand why I dismiss yours."
- Stephen Roberts
