- Pojman, Louis P. In Robert Audi. The Cambridge Dictionary of Philosophy (2nd edition). 1999. "the view that there are no gods. A widely used sense denotes merely not believing in God and is consistent with agnosticism. A stricter sense denotes a belief that there is no God..."
- Nielsen, Kai. Atheism. Encyclopædia Britannica. . 喺2007-04-28搵到;. "Atheism, in general, the critique and denial of metaphysical beliefs in God or spiritual beings... a more adequate characterization of atheism consists in the more complex claim that to be an atheist is to be someone who rejects belief in God for [reasons that depend] on how God is being conceived."
- religioustolerance.org's short article on Definitions of the term "Atheism" suggests that there is no consensus on the definition of the term. Most dictionaries (see the OneLook query for "atheism") first list one of the more narrow definitions.
- Eller, David. Natural Atheism. 2004: p 12. "All humans are born Atheists. No baby born into the world arrives with specific religious beliefs or knowledge. Such beliefs and knowledge must be acquired, which means that they must first exist before and apart from the new life and that they must be presented to and impressed on the new suggestible mind—one that has no critical apparatus and no alternative views of its own."
- Angeles, Peter A. Dictionary of Philosophy. USA: Barnes & Noble. 1981. ISBN 0837120950. "1. the belief that gods do not, or God does not, exist; 2. The disbelief in any kind of supernatural existence that is supposed to affect the universe; 3. the lack of belief in a particular God" 已忽略未知參數
- Runes, Dagobert D.(editor). Dictionary of Philosophy. New Jersey: Littlefield, Adams & Co. Philosophical Library. 1942 edition. ISBN 0064634612. "(a) the belief that there is no God; (b) Some philosophers have been called "atheistic" because they have not held to a belief in a personal God. Atheism in this sense means "not theistic". The former meaning of the term is a literal rendering. The latter meaning is a less rigorous use of the term though widely current in the history of thought" - entry by Vergilius Ferm
- Honderich, Ted (Ed.) (1995). "Humanism". The Oxford Companion to Philosophy. Oxford University Press. p 376. ISBN 0-19-866132-0.
- Fales, Evan. "Naturalism and Physicalism", in Martin 2007, pp. 122–131.
- Baggini 2003, pp. 3–4.
- Drachmann, A. B. Atheism in Pagan Antiquity. Chicago: Ares Publishers. 1977 ("an unchanged reprint of the 1922 edition"). ISBN 0-89005-201-8. "Atheism and atheist are words formed from Greek roots and with Greek derivative endings. Nevertheless they are not Greek; their formation is not consonant with Greek usage. In Greek they said atheos and atheotēs; to these the English words ungodly and ungodliness correspond rather closely. In exactly the same way as ungodly, atheos was used as an expression of severe censure and moral condemnation; this use is an old one, and the oldest that can be traced. Not till later do we find it employed to denote a certain philosophical creed."
- Stanley, Thomas. The history of philosophy 1655–61. quoted in Oxford English Dictionary. 1687. "An Atheist is taken two ways, for him who is an enemy to the Gods, and for him who believeth there are no Gods."