You got me on the definition. An atheist is not someone who denies the existence of God. a·the·ist ˈāTHēəst/ noun a person who disbelieves or lacks belief in the existence of God or gods. "he is a committed atheist" synonyms:nonbeliever, disbeliever, unbeliever,skeptic, doubter, doubting Thomas,agnostic;  nihilist "why is it often assumed that a man of science is probably an atheist?" Agnostic is a synonym of atheist. Atheism is usually defined incorrectly as a belief system. Atheism is not a disbelief in gods or a denial of gods; it is a lack of belief in gods.