D.A. Carson on the Nature of the New Covenant Community

"In the sixth century B.C. the prophet Jeremiah, speaking for the LORD, foresees a time when people will no longer repeat the proverb, "The fathers have eaten sour grapes, and the children's teeth are set on edge" (Jer. 31 :30). The history of Israel under the Mosaic covenant has been characterized by the outworking of this
proverb. The covenantal structure was profoundly racial and tribal. Designated leaders - prophets, priests, king, and occasionally other leaders such as the seventy elders or Bezaleel - were endued with the Spirit, and spoke for God to the people and for the people to God (cj. Exod. 20:19). Thus when the leaders sinned, the entire nation was contaminated, and ultimately faced divine wrath. But the time is coming, Jeremiah says, when this proverb will be abandoned. "Instead," God promises, "everyone will die for his own sin; whoever eats sour grapes - his own teeth will be set on edge" (Jer. 31 :30). This could be true only if the entire covenantal structure associated with Moses' name is replaced by another. That is precisely what the LORD promises: he will make "a new covenant with the house of Israel and with the house of Judah" that "will not be like the covenant" he made with their forefathers at the time of the Exodus. The nature of the promised new covenant is carefully recorded: God will put his law in the hearts and on the minds of his people. Instead of having a mediated knowledge of God, "they will all know me, from the least of them to the greatest," and therefore "no longer will a man teach his neighbor, or a man his brother, saying, 'Know the LORD'" (31:3lff.). This does not foresee a time of no teachers; in the context, it foresees a time of no mediators, because the entire covenant community under this new covenant will have a personal knowledge of God, a knowledge characterized by the forgiveness of sin (31 :34) and by the law of God written on the heart (31 :33). "I will give them singleness of heart and action, so that they will always fear me for their own good and the good of their children after them. I will make an everlasting covenant with them: I will never stop doing good to them, and I will inspire them to fear me, so that they will never turn away from me" (Jer. 32:39-40)."