Honestly, I don’t understand how Avraham Avinu knew the world was created by one G-d. Surely, he was vindicated – by no less than direct prophecy from G-d saying so. But absent that vindication, how are we to believe that he “knew” it, when all the best minds in the world in the next 4,000 years were collectively unable to “know” it.
I know every cheder teaches the story of Avram Avinu this way. I wonder if that is what causes people to seek “proof” for their faith.