Who is the nation of Israel to whom God makes a promise in Jeremiah 31? Jesus gives us a very clear indication in the parable of the landowner:
Matthew 21:43 Therefore I say unto you, the kingdom of God shall be taken from you and given to a nation bringing forth the fruits thereof.
We do not have to look too far to discover which nation, people group that is: it is the church, the church of Jesus Christ, made up of believing Jews and Gentiles, who are the seed of Abraham, the children of God, the real Israelites of the New Testament.
I Peter 2:9-10 writes to the church in these words: But you are a chosen generation, a royal priesthood, an holy nation, a peculiar people … which in times past were not a people, but are now the people of God.
Holy nation is the name given to Israel in Exodus 19:5-6. Peter now applies it to the church! The church is the holy nation, and since the church will never be destroyed, it is in her and not in the modern Jewish State of Israel, that the new Covenant of Jeremiah 31:31-34 is fulfilled. Titus 2:14 is also instructive: to the churches in Crete Paul attributes the title “peculiar people,” a name taken from Exodus 19:5.
One more thing must be noticed in Jeremiah 31:31-34 The promise of the new Covenant is made to the house of Judah and the house of Israel. In this covenant with the house of Israel God will: put His law in their inward parts and write it in their hearts and will be their God and they shall be His people … Moreover, God promises to the same house of Israel: I will forgive their iniquity and I will remember their sin no more. How is this new covenant promise fulfilled, and to whom? The answer is found in Hebrews 8:6-13. This Covenant cannot be with the House of Israel as a separate entity from the church of Jesus Christ. The church of Christ, which enjoys the knowledge of God and forgiveness of sins, is the house of Israel.
Are there, then, no promises to the political entity of the State of Israel? The answer is an unequivocal no. Will Israel as a political entity ever rebuild her temple and worship God as she did in the Old Testament? That is impossible under today’s conditions, but even if they did build a temple in Jerusalem and institute a priesthood, offer sacrifices and celebrate the feasts, it will be just another sign of Jewish apostasy from God. If the sacrifices of the wicked were abominable to God in the Old Testament, Proverbs 15:8, 21:27, how much more abominable would the recommencing of animal sacrifices be in the future after the one, only sacrifice of the Son of God?
All the promises of God are in Christ. 2 Cor. 1:20 All the promises of God were made to Christ, as the Seed of Abraham. Galatians 3:16 Therefore, there can be no promise of any kind for any unbeliever outside of Jesus Christ.
The calling of the Jew, as the calling of the Gentile, is to repent and believe in Jesus Christ and join the church of Jew and Gentile, male and female, bond and free, where there is no difference, and as many as walk according to this rule, peace be upon them and mercy!” For they are the [Christian] Israel of God!Galatians 3:26-29