i was confronted with a guy who thought he knew everything, and in my limited experience, people who think they know everything only think that, because they don't know anything. He was convinced of his own superiority twice whilst i knew him, first time i showed him definitive proof that he was wrong, and second time, when he was convinced he had practically god-like intelligence, i taught my (then) 12 year old sister basic quantum mechanics using a university level textbook, and told him, that put him in his place :)
(my sister is a genius, easily smarter than me, which is something i rarely say about anyone)
Th guy's toxic - avoid him.
Treat him with utmost kindness...
and laugh forebodingly every once in a while without a "reason."
Let him think he/she does, darkly think to yourself this guy is an arrogant insignificant not open-minded to nothing but his ideals type of fool
He's just insecure. Ignore him because there are no benefits from dealing with his type.