Agnosticism is the view that the truth values of certain claims – especially metaphysical and religious claims such as whether or not God, the divine or the supernatural exist – are unknown and perhaps unknowable. In the popular sense of the term, an "agnostic", according to the philosopher William L. Rowe, is someone who neither believes nor disbelieves in the existence of God, while a theist believes that God does exist and an atheist does not believe that God exists. Agnosticism is a doctrine or set of tenets rather than a religion as such.
Thomas Henry Huxley, an English biologist, coined the word "agnostic" in 1869. Earlier thinkers, however, had written works that promoted agnostic points of view, such as Sanjaya Belatthaputta, a 5th-century BCE Indian philosopher who expressed agnosticism about any afterlife; and Protagoras, a 5th-century BCE Greek philosopher who expressed agnosticism about "the gods". The Nasadiya Sukta in the Rigveda is agnostic about the origin of the universe.
Since Huxley coined the term, many other thinkers have written extensively about agnosticism.