Here's another take on the idea of atheism being a matter of faith or not.
Something occurred to me the other day: "God" is a human concept, or rather, a set of human concepts. Atheism can be seen as rejection of these concepts. Even if any of these human concepts have a coincidental similarity to undiscovered things that actually exist, if the concepts aren't rooted in those things, then the concepts themselves can't be considered true.
Typically, one response to atheism is to say that atheism implicitly claims knowledge about what can't be known, and there might be some deity out there somewhere, undetectable, hiding, or on some other plane of existence beyond our ken. However, a deity that shows no indication of its existence whatsoever can't be the object of a claim about its existence, can it?
To use an analogy, consider the claim, "Charles Dickens wrote The Hunt for Red October". I would immediately declare the claim to be false. Would it be valid to rebut my declaration by saying that the claim might possibly be true, since in a universe as large as ours, there might be some creature, entity or collective on some far-flung planet named Charles Dickens, and he/she/it/they might have written some work entitled "The Hunt for Red October"?
I'd argue that this would not be valid. I suppose in an infinitely large universe (or even in a finite universe about which our knowledge is limited), there is always a very small but non-zero chance that any particular part of it might be occupied by some sort of "Charles Dickens" writing some sort of "Hunt for Red October" until we look and see what's actually there, but none of those hypothetical Charles Dickenses would have been the particular Charles Dickens implicit in the original claim.
In the same way, no matter what exists out in the universe beyond our current knowledge, if nobody on Earth knew about it, it couldn't have been the subject of the claim "God exists".