John Calvin's Bible Commentary
Jeremiah 30:22
As this verse and what occurs in the first verse of the next chapter are materially the same, they shall be both explained here. God then says that the Jews would become a people to him, and that he would become a God to them. This mode of speaking is what we meet with everywhere in the Prophets; and it is very expressive, and includes the whole of true happiness. For when have we life, except when we become the people of God? We ought also to bear in mind that saying of the Psalmist,
“Blessed are the people whose God is Jehovah.”
(Psalms 144:15)
It confirms what I have just said, that a happy life is complete in all its parts, when God promises to be a God to us and takes us as his people. The Prophets, therefore, do not without reason so often inculcate this truth; for though nothing else might be wanting to us that could be expected, yet until we feel assured that God is a Father to us, and that we are his people, whatever happiness we may have, it will only end in misery.
But the Prophet expresses himself more fully, when he says, At that time, that is, when God restored his Church, will I be a God to all the families of Israel They had been so scattered, that they were not one body; but God promises the gathering of that Church, from which the ten tribes had fallen off, when they revolted from the family of David. I cannot proceed farther now.