This is a key point. No one claims "There is nothing out there to discover that we haven't discovered yet", however, the fact that we choose to NOT BELIEVE that some particular item ("X") exists out there simply because we have zero evidence for it does not amount to a BELIEF that "X" does not exist.
That may sound a bit clunky but it is at the heart of this discussion.
It is NOT a "belief" (as some on here claim) that Thormalgazine does NOT exist (a thing I just made up and has no evidence for it). No one is "agnostic" about Thormalgazine. In fact no one believes Thormalgazine exists simply because I said the word.
Some on here feel that it is an active belief to fail to believe in something like God.
I understand their position that it is truly "I don't know", but that isn't how we treat it in our daily lives. Every single day we operate under simple rules "There is no elephant that lives in my shed out back", "there is no invisible wall that runs across the interstate".
All these things MIGHT be true but no one thinks it is an active BELIEF to NOT BELIEVE they exist.