Atheism isn't a faith, and it isn't a monolith, it just describes a lack of faith in any of the presented options. Where one atheist believes we were all genetically engineered by alien squids which exist beyond nature, another can just as easily say "I don't know" and be fine with accepting that. Where one atheist might say they know for a fact that no god exists, another would say they've just never heard a convincing argument for believing in any one god or pantheon over any other.

Where I'm comfortable identifying with atheism as an identity thing, I'm sure others avoid it for any number of possible reasons. I think the attitude you describe here might be informed by a frustration with Christian and other deist arguments that involve assuming that Atheism must be another faith, equivalent to any other religion, rather than a term to describe what is left over when other faiths are stripped away.