Bowie, than you just plain have a different definition of atheism and agnosticism than I do - or most anyone else.
Atheism is the belief, faith, conviction, what-have-you (you can say it's "certainty" but so does a religious person about their faith) that there is NOT a God/gods/Force/etc.
Agnosticism is the conviction/belief/idea/faith/etc that you do not know and/or cannot know.
We can go 17 more rounds about theistic agnosticism, apatheistic agnosticism, metaphysical agnosticism, and all that - I'm a philosophy major, seriously, I'll do it if you insist. But this seems a futile discussion. If you're "willing to accept that there's the possibility of a benevolent creator or intelligent design or what have you, but", you're not, in my book, a strict atheist.
Atheism, in the strict definition, is the positive belief in the nonexistence of (a) God(s). Nonbelieve in the existence of God is a much broader, more inclusive definition of atheism - but then there is little to no more room for a "third option". Semantics may often be the basis of understanding, it can also be used to fog things up.