“You shall have no other gods before me.” Exodus 20:3

False gods promise what only the true God provides.  

1 Kings 18:17 When Ahab saw him, he exclaimed, “So, is it really you, you troublemaker of Israel?”

vs. 18 “I have made no trouble for Israel,” Elijah replied. “You and your family are the troublemakers, for you have refused to obey the commands of the Lord and have worshiped the images of Baal instead.

19-21.  Now summon all Israel to join me at Mount Carmel, along with the 450 prophets of Baal and the 400 prophets of Asherah who are supported by Jezebel.”

20 So Ahab summoned all the people of Israel and the prophets to Mount Carmel. 21 Then Elijah stood in front of them and said, “How much longer will you waver, hobbling between two opinions? If the Lord is God, follow him! But if Baal is God, then follow him!” But the people were completely silent.  

Verse 24, Then call on the name of your god, and I will call on the name of the Lord. The god who answers by setting fire to the wood is the true God!” And all the people agreed.

Verse 26, So they prepared one of the bulls and placed it on the altar. Then they called on the name of Baal from morning until noontime, shouting, “O Baal, answer us!” But there was no reply of any kind. Then they danced, hobbling around the altar they had made.

Verse 27, About noontime Elijah began mocking them. “You’ll have to shout louder,” he scoffed, “for surely he is a god! Perhaps he is daydreaming, or is relieving himself. Or maybe he is away on a trip, or is asleep and needs to be wakened!”

vs. 29, But there was no response, no one answered, no one paid attention. 

I Kings 18:36-37, At the usual time for offering the evening sacrifice, Elijah the prophet walked up to the altar and prayed, “O Lord, God of Abraham, Isaac, and Jacob, prove today that you are God in Israel and that I am your servant. Prove that I have done all this at your command. 37 O Lord, answer me! Answer me so these people will know that you, O Lord, are God and that you have brought them back to yourself.”

Verse 38- Immediately the fire of the Lord flashed down from heaven and burned up the young bull, the wood, the stones, and the dust. It even licked up all the water in the trench!

39, And when all the people saw it, they fell face down on the ground and cried out, “The Lord—he is God! Yes, the Lord is God!”