John Calvin's Bible Commentary
Jeremiah 21:5
He proceeds with the subject; and though he afterwards is more diffuse, he yet confirms here what we have just seen, — even that God was the leader of the war, and that the Chaldeans were, as it were, his hired soldiers, whom he guided by his own hand, and to whom he would give the signal to fight.
I, myself he says, will fight against you He put this in opposition to the wonderful works which Zedekiah had mentioned. God, indeed, had formerly been in a wonderful way present with his Church, not only once, but a thousand times; but he says now, “whatever power I have, it shall be exercised now against you; expect, therefore, no aid from me, but know that I am armed, and shall wholly destroy you.” He adds, with an extended hand and a strong arm; as though he had said, “your fathers found wonderful works done for their safety; but you shall by experience learn how great is my power to destroy you.” In short, he means that all God’s power would be a cause of terror to the Jews, and that therefore they could not escape, as there is nothing more dreadful than to have God’s hand opposed to us. To the same purpose is what follows, in wrath, and in fury, and in great indignation (22) God intimates in these words that he would be implacable, and that hence Zedekiah was mistaken when he thought that the end of their evils was nigh at hand.
He might indeed have said briefly, “I will fight with an extended hand and with wrath;” but he mentioned wrath three times in various words. Hence what I have said appears evident, that Zedekiah was deprived of every hope, lest he should deceive himself, as though he would somehow propitiate God, who had already given up the city to final destruction. But we shall see that the Prophet had not ceased from the discharge of his office, and that he had allowed some room for repentance. But he made expressly this answer, for the king could not have been otherwise awakened. We shall see how he explained himself; but this beginning was as it were a thunderclap to lay prostrate the pride of the king and of the people. They had become first torpid in their evils, and then such was their contumacy that they sought to subject God to themselves. As then their stupidity and their obstinacy were so great, the Prophet could not, with any hope of success, have exhorted them to repent and offered them the mercy of God; it was therefore necessary for them to be so smitten as to perceive that they were wholly lost, and that God was so angry with them that they could not be saved by any human means. But we must defer the rest till to-morrow.