On Mount Carmel, who asked the people, "How long will you waver between two opinions?"

Answer: Elijah

Elijah challenged Israel on Carmel: if the LORD is God, follow Him; if Baal, follow him. The people answered not a word.

“Then Elijah approached all the people and said, “How long will you waver between two opinions? If the LORD is God, follow Him. But if Baal is God, follow him.” But the people did not answer a word.”— 1 Kings 18:21 (BSB)