Jer 11:4

“Not everyone who says they are a people of God is a people of God. These people who were proclaimed to be the people of God heard it said to them, "You are not my people." … For "they have provoked me to jealousy with what is not God, … they have provoked me with their idols. So I will provoke them to jealousy with those who are not a people."6We were thus made into a people for God. The righteousness of God was proclaimed to the people who will be born, to a people from the pagan nations. For this people is born suddenly, yet in the prophet it also is said, "Has a nation been born all at once?" But a nation was born all at once when the Savior dwelled among them, and five thousand believed in one day, and three thousand were added in another day, and we see that a whole people is born to the Word of God, and it is said to the barren woman who suddenly bears, who formerly could not give birth before: "Be glad, O barren woman who did not bear, break forth and cry in joy you who have not had birth pains, for the children of the deserted woman are much more than she who has a husband." She was deserted from the law, deserted from God, but that synagogue is spoken of as one who has the law as a husband. What then does God promise me? "You will be my people, and I will be your God." He is the God of none except those whom he favors, as he favors the patriarch to whom he said, "I am your God," and again to another, "I will be your God," and for others, "I will be their God."”

“(Ver. 4.) Cursed is the man who does not listen to the words of this covenant that I commanded your fathers on the day that I brought them out of the land of Egypt, out of the iron furnace, saying: Listen to my voice, and do all that I command you, and you shall be my people, and I will be your Lord (or God). Not because of the privileges of lineage, not because of the injury of circumcision, and the rest of the Sabbath, but because of obedience, God becomes the people of Israel, and Israel becomes his people. And here indeed He speaks as if to slaves, so that they may please God. But in the Gospel, the Lord says to His disciples: 'You are my friends,' He says, 'if you do what I command you. I will no longer call you servants, because a servant does not know what his master is doing. But I have called you friends, because I have made known to you everything that I have heard from My Father.' (John 15:14-15). And when they have become My friends, they pass on to being children: For as many as received Him, He gave them the power to become children of God. (John 1:12). Where he instructs his friends and disciples: Be perfect as your Father in heaven is perfect (Matthew 5:48); he is commanding likeness, not equality. And there is obedience to the commandments, here is the likeness of God. And when he says: On the day when I brought them out of the land of Egypt, out of the iron furnace, he gives us understanding that the furnace and the iron furnace, and the kindling of tribulation and punishment signify magnitude, not a specific place of punishment, prepared with iron material.”