1 Kings 18:40

Elijah required the people to show their conviction by acts - acts which might expose them to the anger of king or queen, but which once committed would cause them to break with Baal and his worshippers forever.

Elijah is said to have slain the “prophets of Baal,” because the people killed them by his orders. Why they were brought down to the torrent-bed of Kishon to be killed, is difficult to explain. Perhaps the object of Elijah was to leave the bodies in a place where they would not be found, since the coming rain would, he knew, send a flood down the Kishon ravine, and bear off the corpses to the sea. Elijah’s act is to be justified by the express command of the Law, that idolatrous Israelites were to be put to death, and by the right of a prophet under the theocracy to step in and execute the Law when the king failed in his duty.