John Calvin Commentary Jeremiah 33:19-21

"And the word of Jehovah came unto Jeremiah, saying, Thus saith Jehovah: If ye can break my covenant of the day, and my covenant of the night, so that there shall not be day and night in their season; then may also my covenant be broken with David my servant, that he shall not have a son to reign upon his throne; and with the Levites the priests, my ministers." — Jeremiah 33:19-21 (ASV)

He confirms the same thing, but by introducing an analogy, for he shows that God’s covenant with the people of Israel would not be less firm than the settled order of nature. The courses of the sun, moon, and stars are unceasing; the succession of day and night is continual. This settled state of things is so fixed that, despite such great and multiplied variety, there is no change. We now have rain, then fair weather, and we have various changes in the seasons; but the sun still continues its daily course, the moon is new every month, and the revolving of day and night, which God has appointed, never ceases. This unbroken order declares, as it is said in Psalm 19, the wonderful wisdom of God.

The Prophet then sets before us here the order of nature and says that God’s covenant with His Church will be no less fixed and unchangeable than His covenant with humankind regarding the government of the world.

We now perceive the Prophet's purpose in saying, If you can make void my covenant respecting the day and the night, then my covenant with David and the Levites shall be abolished. Now he indirectly touches on the wickedness of the people, for the Jews, as far as they could, overthrew God's covenant by their murmurs and complaints. In their adversities, they instantly entertained the thought, and also expressed it, that God had forgotten His covenant.

This lack of faith is then intimated by the Prophet, as though he had said, “Why are these complaints? It is the same as if you sought to pull down the sun and the moon from the heavens, to subvert the difference between day and night, and to upset the whole order of nature. For I am the same God who has settled the succession of day and night and has promised that the Church shall continue forever. You can, therefore, no more abolish my covenant with David than the general law of nature.”

We now then understand the Prophet’s object, for this was not said without conveying reproof. They were very wicked and ungrateful to God when they doubted His truth and constancy regarding the promise of the Church's perpetual condition. In short, he intimates that they were carried away, as it were, by a blind madness when they thus hesitated to believe God’s covenant, as though they attempted to subvert the whole world, so that there would no longer be any difference between light and darkness.

Hence he says, There shall be abolished my covenant with David my servant, that he should not be my son, etc. He repeats what he had said, namely, that it was inevitable that the posterity of David should obtain the kingdom, which we know has been fulfilled in Christ. The throne of David he now calls what he had named before as the throne of the house of Israel, but he means the same thing. It is called the throne of the house of Israel because the king and the people are relatively connected, and also because the posterity of David ruled for the public good, not for their own sake.

He adds, and with the Levites, the priests, my ministers. He had called David his servant; he now calls the Levites his ministers. The word שרת, sheret, is commonly known and is used often by Moses when speaking of the Levitical priesthood. Its meaning is to serve.