Submit your site to Agnosticism if the primary focus of the site is Agnosticism. If Agnosticism is only incidental, then please consider a more appropriate category.
Agnosticism is a term originally coined by Thomas H. Huxley in the 1840s to refer to an ideology which states, primarily, that the nature of the universe and of existence itself cannot be known. Hence, it is foolish to pretend otherwise, and all attempts to the contrary must necessarily end in dogma lacking in all form of proof.
From Huxley's "Agnosticism":
"Agnosticism, in fact, is not a creed, but a method, the essence of which lies in the rigorous application of a single principle ... Positively the principle may be expressed: In matters of the intellect, follow your reason as far as it will take you, without regard to any other consideration. And negatively: In matters of the intellect, do not pretend that conclusions are certain which are not demonstrated or demonstrable."