1 Kings 18:16-21

When Obadiah went and informed Ahab, the king went to meet Elijah.  When Ahab saw Elijah, he said to him, “Is it really you, the one who brings disaster on Israel?”  Elijah replied, “I have not brought disaster on Israel. But you and your father’s dynasty have, by abandoning the Lord’s commandments and following the Baals.  Now send out messengers and assemble all Israel before me at Mount Carmel, as well as the prophets of Baal and prophets of Asherah whom Jezebel supports.  Ahab sent messengers to all the Israelites and had the prophets assemble at Mount Carmel.  Elijah approached all the people and said, “How long are you going to be paralyzed by indecision? If the Lord is the true God, then follow him, but if Baal is, follow him!” But the people did not say a word.0

Elijah assures Obadiah that he will stand before Ahab, and indeed he does. Ahab and Elijah call each other troublemakers, and it should be obvious here that Elijah is in the right. Israel has long "left her first love", and turned to worship idols or other gods, mainly Baal and Ashera. Elijah's proposal is drastic and full of trust in the Lord. He suggests to Ahab to gather all the prophets of Baal and Ashera together, along with people from all over Israel. A public contest is coming to reveal who's God is greater. The Lord, through one man, will place His power and His presence on display to turn a nation back to Himself and reveal belief in other gods as folly. The Lord does great things, even through just one person. Elijah is outnumbered 850 to 1, but His God is infinitely greater.