I think there is a lot of semantic nonsense swirling around the words “agnostic” and “atheist.”
The word agnostic means you can’t be certain. Well, according to quantum mechanics, I can’t be certain that my couch isn’t going to spontaneously turn from solid to insubstantial. There is a very slight possibility that my body will pass through all the atoms in my couch. So therefore, strictly speaking, I’m agnostic about whether or not I’ll fall through my couch if I sit on it.
But I still sit on my couch.
Similarly, I’m agnostic about the existences of Thor, Zeus, Yahweh, Oludamare, Vishnu, Yu Yevon, and all the hundreds of deities posited by human religions. There’s a very slight possibility that Zeus could really exist and everyone is wrong. But nevertheless, I don’t actually spend time worshipping Zeus. I don’t construct hecatombs dedicated to Zeus. Functionally speaking, I do not believe in Zeus, in the exact same way that I do not believe I will fall through my couch.
So in other words, it seems like a lot of people who call themselves “agnostic” are functionally indistinguishable from people who call themselves atheist. In fact, by this definition, I am both an agnostic and an atheist.
But there are other people who understand the word “agnostic” to mean that you are genuinely on the fence. That you’re maybe 50/50 about the possibility of Zeus existing, (or that you’ll fall through your couch), so you construct hecatombs (or OCD-test your couch for solidness every time) “just in case.” I’m not one of these agnostics.