"Behold, days are coming", declares the Lord, "when I will make a new covenant with the house of Israel and with the house of Judah"... "I will put my law within them and on their heart I will write it and I will be their God and they shall be my people."
Jeremiah writes these words as the people of Israel continue to live in exile in a foreign land. The rest of Jeremiah 31 is focused primarily on the promise of Israel's return from that exile. Jeremiah speaks of the day when Israel will no longer live in a foreign land but will return home and see their nation restored. Jeremiah dreams of Jerusalem being rebuilt and the people living under God's rule once again. The people long for their punishment to come to an end; they long to return home.
But in the few verses that make up the sermon text for this week God speaks through Jeremiah to a larger problem that needs to be remedied. Yes, the exile is one very serious problem that needs to addressed. But it is mostly just a symptom of the real problem; Israel's unending cycle of sin and idolatry. It is that sin that landed them in this mess in the first place. Furthermore, the exile was not the result of one sin or even one generation's sins. It was the result of the piling up of the sins of generation after generation. Much of the Old Testament could be seen as a record of the inability of Israel to avoid sin. Therefore, Israel needs more than just deliverance from their exile. They are also in desperate need of deliverance from their slavery to sin.
This is what the new covenant promises. God says through Jeremiah that one day he will take the Law that had been written on stone tablets and write it on the hearts of the people. The people will no longer have to teach each other about God because they will all know God. This is a promise that God will grace his people in such a way that the power of sin over them will actually be broken and the cycle of sin can come to an end. It is a promise that God will take steps not only to treat our symptoms but to heal us of our illness.