Weak atheist is defined as anyone who lacks belief in the existence of any gods. The definition of weak atheist is the same as the general definition for atheist. The term weak atheist is normally used as a contrast with the narrower term strong atheist which is defined as one who positively asserts that no gods exist.
Some people deny that weak atheists exist, confusing the term with agnostic. This is a mistake because atheism is about (a lack of) belief whereas agnosticism is about (a lack of) knowledge. Belief and knowledge are related but separate issues. Thus whereas a weak atheist is one who does not believe in any gods, an agnostic is one who does not claim to know if any gods exist or not. An agnostic is also either a weak atheist or a theist of some sort. The label weak atheist overlaps with negative atheist and implicit atheist.
"Weak atheists do not find the evidence for the existence of gods persuasive. While theists say that deities, or gods, do exist, weak atheists do not necessarily disagree. Some simply hold no opinion on the matter. Others more actively have doubts that gods exist. They consider it likely that gods do not exist because no one can prove that they do. In this respect, weak atheism is similar to agnosticism, or the view that gods might or might not exist but no one can know for certain."
- World Religions: Primary Sources, Michael J. O'Neal and J. Sydney Jones
