Yeah well, there is some confusion around the terms “atheist” and “agnostic”, and different people draw drastically different conclusions when hearing these terms. As far as I’m concerned — the former is about what you believe, and the latter is about what you claim to know. You can therefor be any combination of theistic/gnostic.

Furthermore, I would take a wild guess and say most atheists don’t claim to know with absolute certainty that there is no god; in most cases you can assume an atheist is also an agnostic.

In that regard, I don’t think Dawkins claims to “know” anything either, he basically uses the FSM explanation, and raises facts about different religions in the world and throughout history, which make religion seem unreliable, and the existence of a god (as he was defined so far) seem unlikely.