It is becoming increasingly more common for atheists to define atheism, not as the denial of the existence of God, but as a lack of belief in the existence of God. As such, these atheists maintain that atheism is merely the lack of any affirmation of the existence of God.
Atheist B. C. Johnson says, “Theists believe in God, while atheists do not have such a belief. Many theists insist that it is the responsibility of the atheist to offer evidence justifying his lack of belief in God. But is the theist’s demand rational? Must the atheist justify his lack of belief in God? Or does the burden rest with the theist? [B. C. Johnson, The Atheist Debater's Handbook (Buffalo: Prometheus Books, 1983): 11] Atheist Doug Krueger writes, “The term ‘atheism’ is from the Greek atheos. The prefix ‘a’ means ‘without,’ and the Greek theos means ‘god,’ so atheism means simply ‘being without god.’ Theism asserts that there is a god, so atheism is the view which does not assert that there is a god.” [Douglas E. Krueger, What Is Atheism? A Short Introduction (Amherst, NY: Prometheus Books, 1998): 17] (Notice, by the way, the fallacious move in Krueger’s reasoning. He goes from the ‘not’ (from the Greek alpha) modifying ‘God’ (which is what the Greek has) to the ‘not’ modifying ‘assert.’ This allows him the semblance of grounding his position in the etymology of the Greek while illicitly concluding that atheism is the absence of the assertion of God instead of the negation of God as the Greek actually says.) Atheist George H. Smith claims, “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.” [George H. Smith Atheism: The Case Against God (Buffalo: Prometheus Books, 1989), 7, emphasis in original] In his debate with Christian philosopher Greg Bahnsen Smith says, “There is no atheistic worldview. Let’s be clear about that. Atheism is simply the absence of belief in God.”
Aside from the issue of whether this is a legitimate definition of atheism and aside from the issue of the rhetorical legitimacy of this move (since, as I would argue, it is an attempt to illicitly shift the burden of proof entirely to the theist and to mitigate the rational responsibility of defending one’s own worldview) there is another interesting aspect to this re-definition matter. This definition of atheism entails the quirky conclusion that atheism is logically compatible with theism. This is so because if atheism is the lack of a belief in god, then it could be the case both that atheism is true (i.e., it could be the case that George Smith, for example, lacks the belief in God) while at the same time that God actually exists. The only thing that theism is logically incompatible with is that God does not exist. I will be willing to grant this eccentric definition of atheism if the atheist will acknowledge that, even if his atheism is true, it could still be the case that God exists. Strange indeed.