Implicit atheism and explicit atheism are types of atheism coined by George H. Smith (1979, p. 13-18). "Implicit atheism" is defined as "the absence of theistic belief without a conscious rejection of it", while "explicit atheism" is "the absence of theistic belief due to a conscious rejection of it". Explicit atheists have considered the idea of deities and have rejected belief that any exist. Implicit atheists, though they do not themselves maintain a belief in a god or gods, have not rejected the notion or have not considered it further.