Jer 31:33 But this is the covenant that I will make with the house of Israel after those days, declares the LORD: I will put my law within them, and I will write it on their hearts. And I will be their God, and they shall be my people. Jer 31:34 And no longer shall each one teach his neighbor and each his brother, saying, 'Know the LORD,' for they shall all know me, from the least of them to the greatest, declares the LORD. For I will forgive their iniquity, and I will remember their sin no more."
These are familiar words to any Christian who cares about what we are in Jesus Christ. He told us when he instituted the Lord’s Supper that by his death the New Covenant was established. This immediately makes it of primary importance to those redeemed by the cross.
The above verses explain four things that the New Covenant does for Christians. Two are mostly agreed upon by saints in general but the other two interestingly are not always seen the same by all saints. This is too bad because of the importance of the subject. As I said, these are the four effects of the cross obviously foretold in the OT. Let me give my understanding especially of the two not always agreed upon.
The two that are generally agreed on are the forgiveness of sins and the writing of his law on our hearts. Most would understand this writing of the law on our hearts as taking place when he gives us a new nature when the Holy Spirit indwells us at conversion. We are no longer rebels but now love the Lord and love his law or his will for us. A lot can be said of the different takes on the forgiveness of sins but that is not my point in this article.
This article is mostly about the other two points. Firstly, in vs. 34 we are told that everyone under the NC will know the Lord, everyone! Under the OC one was born into the covenant and was circumcised as a baby, if a male, to show that you were in. In this sense the child had no idea who his God was but it didn’t matter because his father brought him into this covenant by his will when he circumcised him. We are being told that the NC is not physical and so one doesn’t enter it by the will of man or a physical act, Joh 1:12 But to all who did receive him, who believed in his name, he gave the right to become children of God, Joh 1:13 who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. We enter the kingdom by the will of God as he enables us to repent and believe. Because of this even if a young person is saved he must understand the gospel and enter through belief. Someone else can’t do it for him or force him in like in the OT. If you are saved you know who God is and you know how you were saved. Someone won’t come along later and explain how you were brought into a relationship with God because it can’t happen apart from your understanding it in the first place.
In this the NC is fundamentally different than the OC because it is a spiritual kingdom not a physical one. You can’t enter it by moving from one place to another but by spiritual rebirth, not physical birth; it couldn’t be clearer. And this is why we stand with millions throughout church history who suffered horribly but would not baptize their children and would re-baptize converts who had been sprinkled as babies. For an unconverted person to be baptized (and eat communion as well) is to act out a lie because they are illustrating something that they have never actually had happen to them.
Paul explains this clearly in Rom 2:27 Then he who is physically uncircumcised but keeps the law will condemn you who have the written code and circumcision but break the law. Rom 2:28 For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. Rom 2:29 But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.
The fourth point in Jer. 31 is that he will be our God and we his people, 33. The end result of forgiven sins is peace with God and a new nature in which we love him and come to know him and all this in turn restores to us the right relationship with him that we were created to have; we are no longer rebels but worshippers. It isn’t just about us making it to heaven instead of hell even though we don’t really like God, but we “get saved” because being around him is better than burning. This seems to be the attitude of many professors who don’t have any time for God. They “become Christians” to get him off their backs so they can get on with worshipping the true love of their lives, themselves.
So what we have in the NC and why it is so much better than the old one is that by giving us his Spirit we are empowered to love God and serve him as he desires to be served. The OC which was one of exterior law did not come with power to change a sinner and so was ineffective. Too many today think that Christianity is merely God forgiving sinners and completely fail to realize that the great promise in the OT concerning the New Covenant was God in us which causes a transformation of life, Col 1:26 the mystery hidden for ages and generations but now revealed to his saints. Col 1:27 To them God chose to make known how great among the Gentiles are the riches of the glory of this mystery, which is Christ in you, the hope of glory.
Any form of Christianity that doesn’t teach and demand a transformed life isn’t biblical Christianity.