Wolf:
Our fundamental belief is that G-d exists as one controlling all powerful being as a matter of simple logic.
Otherwise, we could not be held accountable for any of our actions, since we could defend that we did not know G-d existed, or that there was not another god for us to serve. This is discussed by R’ Elchonon Wasserman, where he posits that every person in the world is responsible for the 7 mitzvos bnei noach by due of its being obvious that there is One G-d.
Har sinai only shows that there is a G-d who gave us a torah, it does not presuppose the existence of Zues and his cronies on Mt. Olympus.
I’m sorry if this is against science, but the existence of the world proves beyond any doubt that there is One G-d. Anyone who doesn’t believe that doesn’t really believe that there is One G-d, so they are an apikores and they should make kiddush on mevushal wine because their wine is yayin nesech.