"Agnosticism" is the belief that one either cannot know, or cannot decide, whether God exists. The term was coined by [[http://en.wikipedia.org/wiki/Thomas_Henry_Huxley Thomas Henry Huxley]] in 1869, though the concept has been [[http://www.uctaa.net/articles/meds/med13/med244.html kicking around for much longer]]. Agnostics usually appear under the category of "non-believers" along with atheists. Incidentally, whilst there is a degree of overlap, agnosticism is not the same as UsefulNotes/{{atheism}}. Agnosticism is distinct in the sense that whilst agnostics do not necessarily believe in God, they do not ''disbelieve'' in God either. While agnostics generally agree with atheists on the subject of belief in God or gods, they disagree on the subject of disbelief: a common agnostic criticism of atheism is the scientific principle that "absence of proof does not consitute a disproof".

There are many different strands of agnostic thought, including the following :
* belief that God is inherently "unknowable". Adherents to this type of agnosticism believe that one ''cannot'' know of God's existence, role, appearance or ethics (assuming that he might exist at all).
* belief that God's existence is neither proven nor disproven. That is, that while God may be "knowable", we do not "know" yet either way.
* agnostic atheism, where God probably does not exist based on the evidence at hand, but it is not impossible that one does.
* agnostic theism, where God probably exists based on the evidence at hand, but that it is not certain.
* apatheism (a {{portmanteau}} of "apathy" and "theism"), where the individual simply does not care whether god does or does not exist, or finds no practical reason to believe either way.

Agnosticism can also be used to describe someone who is undecided, or just non-committed to any particular belief. For example, in experimental physics, there is a concept called "model agnosticism", which describes a state of mind in which the experimenter has multiple theories (or "models"), but keeps an open mind about which of them is true pending the results of the experiment.

Agnostics have on occasion been condemned by followers of various religions for their lack of belief (often being lumped in with atheists in the process). They have also been criticized by prominent atheist UsefulNotes/RichardDawkins for "fence sitting" -- i.e. not having the conviction to outright admit to being an atheist. Many agnostics find this insulting, and parallels have been drawn between agnosticism and bisexuality, as bisexuals can also face discrimination from both ends of a spectrum on similar grounds.