Agnosticism privileges the religious argument. It says that the religious argument is, at least, as likely as the Atheist argument. However, while the Atheist argument actually has supporting evidence (take a key feature of that argument: "The Universe requires no gods to exist." Then, Occam's Razor.) the religious argument rests on assumptions that rest on other assumptions- turtles all the way down.
It's not that lack of evidence is evidence against the religious argument; it's that to get to THAT point is impossible for the religious argument. They don't meet even the slightest burden of proof. The extraordinary claim is not that Atheism is the only factually, scientific, based "religious" position; but that "god" exists. The religious would need to prove- which they haven't- that it's even Possible for god to exist in the universe we find ourselves.
I am not Agnostic. I am not "99% sure". I am 100% positive that Atheism is correct.
"But wait!" You scream, if past conversations are any indicator. "What if..."
If wishes were fishes we'd all have a wonderful dinner. I'm 100% sure, in the exact same way that I am 100% sure Harry Potter is a fictional character and not a real boy. Just because some guy once said some thing and every body believed him, doesn't mean it's True. And as I've shown: The Arguments aren't even close to evenly matched.
There's no reason to accept, assume, or suggest that the Religious argument is even Possible. Sincerity of belief doesn't protect that belief from falsehood. There's as much reason to caveat Atheism with the "Agnostic Position" as there is to caveat your every day with "... well, only until Kirk and Spock beam down and retrieve me." Fiction is not fact.