That’s agnosticism. There is an element of agnosticism involved, but they are separate. Atheist simply means that one does not believe in any gods. Agnosticism/Gnosticism would be a statement about certainty any god(s) existing or not existing. One could be a theist and agnostic. Without actual evidence, I don’t believe anyone go claims to be gnostic regardless of whether they are theist or atheist. But you also positively assert all known God’s don’t exist? I positively assert that I do not believe in any of the thousands of possible gods that have been proposed as none of them have compelling evidence. I further assert that I’m not that different from the vast majority of theists (those who believe in one or more gods). The theist has some set of gods that they believe exist and that all of the other possibilities do not exist. I just take a step further and don’t believe their god(s) exist, either. So you believe that any potential deity is fundamentally unknowable by humans? No. I don’t try to make any kind of super-natural claims. I only state that I have seen no compelling evidence that any gods exist and therefore I do not believe in them. Could a god exist, including with unknown evidence, that hasn’t been discovered? Sure… science makes new discoveries all of the time. My expectation, even then, is that it will simply be something sufficiently advanced and/or obscure that we just don’t recognize it. I would remain very skeptical of any attempts to describe it as super-natural.