Do not call someone a fool
Matthew 5:22, “But I say to you that everyone who is angry with his brother shall be guilty before the court; and whoever says to his brother, ‘You good-for-nothing,’ shall be guilty before the supreme court; and whoever says, ‘You fool,’ shall be guilty enough to go into the fiery hell.”
Calling someone a fool
Psalm 14:1, “The fool has said in his heart, “There is no God.” They are corrupt, they have committed abominable deeds; There is no one who does good”
Matthew 23:17, “You fools and blind men! Which is more important, the gold or the temple that sanctified the gold?”
3474 mōrós (the root of the English terms, "moron, moronic") – properly, dull (insipid), flat ("without an edge"); (figuratively) "mentally inert"; dull in understanding; nonsensical ("moronic"), lacking a grip on reality (acting as though "brainless").