What was the Mount Carmel controversy between Elijah and the prophets of Baal about?
The Mount Carmel controversy centered on idolatry and pagan worship. Elijah confronted the prophets of Baal because Israel, despite having proof of the living God from their beginning, had followed after false gods. This clash exposed the human bent to worship a false god, an innate tendency present since the Tower of Babel.
Les explains that the Mount Carmel controversy was about Israel's idolatry and pagan worship. He connects this to the list of sins in verse 20—idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, and heresies—which can be lumped together as idolatry or pagan worship. He points to Jeremiah 44 as an example, noting this bent to worship a false god has plagued the human race since the Tower of Babel. Even Israel, who had proof of the living God from their beginning and should have known better, followed after pagan gods. That was the controversy Elijah had on Mount Carmel with all the prophets of Baal; Israel had been following them.