Definition of "atheism"

A non-belief in deities.

1. (strictly) Belief that no deities exist (sometimes including rejection of other religious beliefs).  quotations  examples

   Quotations

   • For atheism to be rationally justified it is only necessary that it be more probable than not or at least more probable than theism. Certainty is no more required in the case of atheism than it is in the case of scientific theories.

     2002, Michael Martin, “Should atheists be agnostics?”, in Julian Baggini, editor, The Philosophers' Magazine‎, number 19, archived from the original on 20 December 2002, page 18

2. (broadly) A lack of belief in deities, or a belief that there is insufficient evidence to believe in a god.  quotations  examples

   Quotations

   • The theory of Secularism is a form, not of dogmatic, but of skeptical, Atheism; it is dogmatic only in denying the sufficiency of the evidence for the being and perfections of God. It does not deny, it only does not believe, His existence.

     1857, James Buchanan, Modern Atheism: under its forms of Pantheism, Materialism, Secularism, Development, and Natural Laws‎, Boston: Gould and Lincoln, page 365

   • ...but Atheism per se simply means, not denial, but rejection, in the sense of not accepting the Theistic theory of the universe which Mr. Lee has put forward tonight.

     1896, George William Foote with W. T. Lee, “First Night”, in Theism or Athiesm: Which is the more reasonable?‎, London: R. Forder, page 17

3. (very broadly) Absence of belief that any deities exist (including absence of the concept of deities).  quotations  examples

   Quotations

   • What can parents do, and mothers more especially, […] with regard to the atheism that is natural to all the children of men?

     1829, John Wesley, Sermons, on Several Occasions, 10th edition, volume 2, page 373

   • Atheism, in its basic form, is not a belief; it is the absence of belief. An atheist is not primarily a person who believes that a god does not exist; rather, he does not believe in the existence of a god.

     1979, George H. Smith, Atheism: The Case Against God, Buffalo, New York: Prometheus, LCC BL2747.3.S6 1979, page 7

(historical or rare) Absence of belief in a particular deity, pantheon, or religious doctrine (notwithstanding belief in other deities).  quotations

(obsolete) Absence of belief in the One True God, defined by Moore as personal, immaterial and trinitarian (thus Islam, Judaism and unitarian Christianity), as opposed to monotheism.

(sometimes proscribed) A rejection of all religions, even non-theistic ones.  quotations  examples