I might be the person that FLS mentions as having started a
thread a while ago on this topic. My position was that "atheism/agnosticism" is a distinction which provides no useful or philosophically coherent distinction. That is, you can describe an "agnosticism" that makes sense--but if so then it is simply coterminous with what the vast majority of atheists hold to be their position. Or you can describe an "atheism" that makes sense, but if so it in fact describes the actual (though often unrecognized) position adopted by the vast majority of self-described "agnostics."
You can see this in the way that each defines the other position. Self-described "agnostics" will always say that atheists "believe in" or "have faith in" the absolute non-existence of gods--that they are just as "dogmatic" as the religious believers. That, of course, is absurd. Similarly, self-described atheists see agnostics as "wishy-washy" types who want to have a bob each way: despite having no evidence of god's existence they somehow want to insist that this leaves God in a different category from all the other things for which they find no evidence. That, too, is an absurd position (though one which some self-described agnostics do, in fact, hold).
What I mostly discovered from that thread is that the division doesn't serve any useful philosophical purpose bu that it serves a vital social purpose. That is, people who call themselves "atheists" are held to be bumptious and rude (they're saying that believers are "wrong"), while people who call themselves "agnostics" can feel like they're not treading on anybody's deeply held beliefs, and can also feel that they're leaving themselves open to some future conversion experience.
I quite like the idea of "ignosticism" simply because it gets us away from these two rather useless terms. My problem with it, though, is that I am not persuaded that the concept of God is inherently unknowable. In fact, that seems to me to beg the question (by assuming the impossibility of omnipotence). Grant me an omnipotent being, and it is trivially obvious that that omnipotent being has the
ability (if not, apparently, the will) to make his existence known to us, and known absolutely. An omnipotent being need not work through the mechanism of "evidence" (stars rearranged etc.); an omnipotent being can simply make it to be the case that we know that he exists, and know that that knowledge cannot be false.
If, therefore, it remains conceivable that there is a god out there (just as it is
conceivable that there are unicorns, fairies etc. etc.) AND that the question of that god's (or gods') existence is in principle one that can be determined at some future date, it seems to me that we are left with the existence of God being a meaningful postulate for which no evidence has, as yet, been brought forward. Personally, I think that the only sound philosophical position to take towards such a case is the same as the position we take towards the existence of unicorns, fairies, goblins, leprechauns etc. Whether we call that position "atheism" or "agnosticism" isn't all that important to me, but I do think it would be nice if we could all agree that there aren't two distinct, coherent, defensible positions that are described by those terms.