Does not mean they become joined or are included into the Abrahamic or Mosaic Covenants.
Let's be honest here. The New Covenant prophesied in Jeremiah 31:31-34 is between God and the House of Israel. There are no Gentiles mentioned in this covenant. The New Covenant came into fulfilled existence on the day of the Jewish Feast of Harvest which is also called Pentecost. Three thousand Jews were born-again that day. Acts 2:47 says "Christ added to His Church daily such as should be saved" which means more Jews became born-again and saved as per the New Covenant content.
When a Gentile becomes born-again, they are joined to Christ. When a Jew becomes born again, they are joined to Christ and remain in the Abrahamic and Mosaic Covenants. This was the issue with Jewish Christians who were concerned about their standing in the Abrahamic Covenant. So, Saul writes:
28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus.
29 And if ye [Jews] be Christ’s, then are ye [Jews STILL] Abraham’s seed, and heirs according to the promise.
Gal. 3:28–29.
The "Greek" here refers to Gentile proselytes who were closest to Judaism and the Jewish nation through their circumcision and vows to the Torah. Every other non-proselyte Greek was opposed to Israel and had nothing to do with the Jews. They were two separate communities. They did not mingle with each other. The Jews saw them as unclean. And they were. But oh, you say, Judaism is no longer or passed away. Not so. For the four decades that followed Pentecost everything that happened in Jerusalem and Israel happened to the Jews and Gentile proselytes and also God-Fearers such as Cornelius until the destruction of the Jewish Temple and then God began to bring in Gentiles. And then what happened?
In time Gentiles took over what belonged to Israel and stole their covenants and promises and prophecies and made them their own. And for 1900 years they re-interpret history and taught God "cast away His people" and replaced them with the Gentile "Church." All one need to do is read the writings that came later by Gentiles.
And the "heirs according to the promise"? The only people that possessed the promise and were heirs to it were the Jews. So, it's clear that Saul is writing to Jewish Christians who had concerns about their standing in the Abrahamic covenant specifically, and their relationship to God in general.
But just because a Gentile is born again does not mean they are now in the Abrahamic and Mosaic Covenants. That would be impossible because these covenants were made with Abraham and His seed and Gentiles are NOT his seed. Be honest about it. But oh, "when we become Christian, we are added to the covenant." WHERE in the Law, Psalms, and Prophets does it say that? The Hebrews Scriptures are the central hub of everything that happens to Israel, not the New Covenant writings. All New Covenant events during the four decades before the destruction of the Temple was a Jewish phenomenon, not Gentile. Just because a few uncircumcised, non-covenant Gentiles became born again and the Jews held a council in Jerusalem to deal with this fact, what was their decision? They were told to follow certain precepts of the Mosaic Law. Why did they direct them to the Law? Because it was THEIR covenant and they had to muddle through it the best they could. But when the Romans came and destroyed their nation and their Temple God's clock didn't stop. Now, it was time to bring in Gentiles in greater number.
Any born-again Gentile since the destruction of the Temple - and even before - were joined to Christ not the covenants. And there is a difference. Because when the Times of the Gentiles ends, and it will end with the destruction of Gentile nations whether through nuclear war or some cataclysmic event from space, the majority of these nations all contain Gentile Christians. Israel is the House of God. If you want to claim to be in the House of God and thereby in the covenants through Christ, then accept what's coming. Because what's coming is judgment that begins in the House of God. There is no escape. There is no rapture. The end-time prophecy to Israel - the "book" of Revelations - mentions nothing about a rapture. God has no covenant with Gentiles. Why would God remove Gentile believers from the judgment coming upon the world when judgment begins in the House of God? Contradiction.
Gentiles that are born-again are joined to Christ, NOT any of the Hebrew Covenants and do you know why?
Because you are NOT Abraham's seed and heirs according to the promise God made with Hebrews/Jews. Not even Gentile proselytes were seen as being in covenant with God. That's because they are not the seed of Abraham. But oh, we are "spiritual" Israel. Again, NO. When the Holy Spirit began to baptize Jews into Christ [="anointing"] they became spiritual Israel. And spiritual Israel is natural Israel.
May God open your Gentile eyes to see that for 1900 years Gentiles have stolen Israel's covenants and their inheritance. Stop the Steal, as it has been said with regard to the 2020 presidential election. Now apply it to Israel's election before God. It's their covenants. It's their inheritance. It's their Scriptures. He's their Messiah, not yours. If anything, you're only enjoying the BLESSINGS of Abraham as the proselytes did. But never were they, or you, ever considered by Scripture or God or the Jews as being included in the Hebrew covenants.
Stop the Steal.
