To state that atheism is, at minimum, the simple lack of a god belief is called the weak definition for the word atheism (sometimes called negative atheism). Those who use the weak definition tend to include even infants and imbeciles as atheists, based upon the fact that these people are unable to comprehend a god claim and thus lack a god belief. This definition naturally includes those who strongly assert that no gods exist -- and everyone in between.
The strong definition says that atheism is the assertion that no gods exist. Those who advocate the strong definition tell us that an atheist is "a person who maintains that there is no God, that is, that the sentence 'God exists' expresses a false proposition." [18]
The strong definition, however, requires that we come up with another term to describe those who simply lack a god belief. Many atheistic philosophers prefer the term nontheists. [19] Strong atheists, theists, and agnostics describe a middle category, agnostics, though this does not address the simple lack of belief. With the weak definition, nontheism equals atheism, and agnostics are either theistic agnostics or atheistic agnostics.