Here is the prophecy that was fulfilled by Christ through establishment of the new covenant. The old covenant that it replaces was the 'contract' God made with God's people through giving of the law. But the people broke their side of the covenant; that is, they broke the Law.
Laws may compel Obedience through a system of rewards and punishments, but something more is necessary to change people. The new covenant is that "something more." Christ does not merely invite us into the Kingdom of God, he brings us into the kingdom. There we live, not by coercion of laws but by "the law written upon our hearts."
What value is there in a system of rewards and punishments?
What is the relationship between the Old and New Testament?
How is the Law written upon our hearts? (Jeremiah's thought is expanded in Hebrews chapters 8-10)
PRAYER: Grant your Holy Spirit to us, O God, and write your Law on our hearts. - AMEN!