Why will the Lord make his words a fire in Jeremiah’s mouth?

Jeremiah now reveals the Lord’s response to the people’s arrogant rejection of his word in  Jeremiah 5:12–13. Thus says the Lord, the God of hosts. This description of the Lord speaks of the Lord’s ultimate power and authority over the whole universe.¹ By drawing attention to the Lord’s power over all forces that exist, Jeremiah is answering the accusation that the Lord will do nothing (Jeremiah 5:12) because he is unable to.² Indeed, the Lord is powerful and will act.

Jeremiah now tells the people what this all-powerful Lord says: Because you have spoken this word. The you is plural and is referring to what the people have said about the Lord and his prophet in Jeremiah 5:12–13.³ Because they have spoken this way about the Lord, he now says to Jeremiah, I am making my words in your mouth a fire, and this people wood, and the fire shall consume them. The Lord’s word of judgment that Jeremiah speaks will indeed not fail (see Jeremiah 1:9–10). The Lord is not simply speaking judgment on Judah, but he is showing both the people and Jeremiah that his word is indeed true. The Lord’s judgment on his people is coming for many reasons, but the one highlighted here is the fact that they reject his word. The people thought they were dealing with the wind, but the Lord will show them that his word is literally fire, not to refine, but in this case, to destroy.⁴