Commentators explain that Jephthah is not validating the existence of Chemosh. Instead, he is using a clever rhetorical argument based on his opponent's own beliefs. He is essentially saying, 'You believe your god gives you the right to possess land, so you must understand why we insist on possessing the land our God, Yahweh, has given us.' This approach uses the Ammonites' own logic to justify Israel's position.