Elijah destroyed the prophets of Baal to oppose Baal worship. The incident happened in the Old Testament of the Bible, in the book of 1 Kings 18. Elijah was a prophet of God and he challenged the prophets of Baal to a contest on Mount Carmel. They were to each offer a sacrifice and call upon their respective gods to send down fire from heaven to consume the sacrifice. The prophets of Baal called upon their god, but nothing happened. Elijah, on the other hand, called upon the Lord God of Israel, and fire came down and consumed his sacrifice. Elijah then seized the prophets of Baal and killed them all, to show that the Lord God of Israel was the only true God and to put an end to the worship of Baal.