Assuming good faith, do you accept that the question of whether or not atheism is a belief ultimately depends on numerous scientific, philosophical and linguistic assumptions that are legitimately debatable?
I see it as a purely semantic issue with the theists who understand the agnostic atheist's position, not anything substantive.
I also find arguments about it being a belief coming from people that don't know what most atheists believe pretty meaningless. For them, this issue begins by assuming that atheists are lying when the say they have no god belief, that they actually believe that gods don't exist and are looking for ways to avoid having to defend that position, so they lie about their beliefs calling them unbelief. They object to this imagined reality, and are trying to reveal that the atheist is lying.
For them, it is not a purely semantic issue - what to call something - but one of what that something actually is, a substantive issue. These are the people calling atheists liars. How many times have you read that in this thread alone?
But regarding those who do know what the agnostic atheist's position is, and want to call atheism a belief anyway, although I disagree with the usage of the word belief there, it's purely a semantic issue of no substantive relevance. Call it what you like. It makes more sense to me to call my atheism unbelief just as it makes more sense to call myself an agnostic atheist than to pick only one of those words, even if others choose to use the language differently.
There is a big difference between disagreeing about what something is and what to call it. If I say that Constance said something, and you insist it was Missy, there's a big difference between whether we are discussing two different people, in which case it's a question of fact, and whether we are talking about the same person using both a given name and a nickname, in which case it is a semantic argument, and not worth debating. You can go on calling her Missy because she is your sister, and I will go on calling her Constance because she is my supervisor at work. There is no substantive disagreement about what (who) we are talking about. There is nothing to debate.
So, no scientific and philosophical assumptions, so nothing to debate there, and yes to linguistic (semantic) preferences, so nothing to debate there, either, with the theist who actually understands the agnostic atheist's position. If that's you, then there is nothing else to resolve, so where does debate enter?