The epistemological stance that knowledge is only as certain as the available evidence. It is skepticism, especially as pertaining to questions of religion. Agnosticism is consistent with atheism.
A - without Gnosis - intuitive knowledge of spiritual truths (as claimed by the gnostics).
Here is the unarguable "horse's mouth" (Huxley coined the word) Quote:"...it is wrong for a man to say that he is certain of the objective truth of any proposition unless he can produce evidence which logically justifies that certainty. This is what Agnosticism asserts; and, in my opinion, it is all that is essential to Agnosticism. That which Agnostics deny, and repudiate as immoral, is the contrary doctrine, that there are propositions which men ought to believe, without logically satisfactory evidence." ("Agnosticism and Christianity and Other Essays", Thomas Henry Huxley 1889, Buffalo, NY: Prometheus, 1992, p. 193.)
So an agnostic, asserts that the natures or attributes of the gods are unknowable except through the intuition. This of course, has as the corollary, as Huxley (as a Deist) most certainly meant, the proposition that gods exist in some shape, form and quantity, albeit "necessarily" objectively unknown (and sometimes meant as an assertion that these attributes are unknowable) to the agnostic (and sometimes meaning to everyone).