From Lectures on Jeremiah (1563)

Jeremiah shows more clearly how much more abundant and richer the favor of God will be towards his people than formerly. He does not simply promise the restoration of that dignity and greatness which they had lost, but something better and more excellent. We hence see that this passage necessarily refers to the kingdom of Christ, for without Christ nothing could or ought to have been hoped for by the people, superior to the Law. For the Law was a rule of the most perfect doctrine. If then Christ be taken away, it is certain that we must abide in the Law.

We conclude that the prophet predicts of the kingdom of Christ. And this passage is also quoted by the apostles, as being remarkable and worthy of notice (Rom. 11:27; Heb. 8:8; Heb. 10:16).

As to the new covenant, it is not so called because it is contrary to the first covenant. For God is never inconsistent with himself. Nor is he unlike himself, he then who once made a covenant with his chosen people, had not changed his purpose, as though he had forgotten his faithfulness. It then follows, that the first covenant was inviolable. Besides, God had already made his covenant with Abraham, and the Law was a confirmation of that covenant. As then the Law depended on that covenant which God made with his servant Abraham, it follows that God could never have made a new, that is, a contrary or a different covenant. Where do we derive our hope of salvation, except from that blessed seed promised to Abraham? Further, why are we called the children of Abraham, except on account of the common bond of faith? Why are the faithful said to be gathered into the bosom of Abraham? Why does Christ say that some will come from the east and the west and sit down in the kingdom of heaven with Abraham, Isaac, and Jacob (Luke 16:22; Matt. 8:11)?…

The new covenant then was made when Christ appeared with water and blood, and really fulfilled what God had exhibited under types so that the faithful might have some taste of salvation. But the coming of Christ would not have been sufficient, had not regeneration by the Holy Spirit been added. It was, then, in some respects, a new thing, that God regenerated the faithful by his Spirit, so that it became not only a doctrine as to the letter, but also efficacious, which not only strikes the ear, but penetrates into the heart, and really forms us for the service of God…

The Gospel brings with it the grace of regeneration: its doctrine, therefore, is not that of the letter, but penetrates the heart and reforms all the inward faculties, so that obedience is rendered to the righteousness of God…. He adds, “I will be to them a God, and they shall be to me a people”… For as we are aliens from the kingdom of heaven, God reconciles us to himself and testifies that he will be our God.

John Calvin (1509-1564) was one of the most influential theologians of the Protestant Reformation, who served for many decades as the chief pastor of Geneva. He wrote commentaries on most books of the Bible, which were reworked from lectures he gave to theological students. He is commemorated on May 26 or May 28 on the liturgical calendars of several Anglican churches.