Then the Apostle Paul must have been a little confused in the verses below, where he makes it clear that being a Jew is not about one's bloodline.
Rom 2:28 For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh:
Rom 2:29 But he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God....
Paul said God has made all nations of one blood, so how could a Jew have a different bloodline than a Gentile?
It's about God's election and promises, and the tribes of the nations can be redeemed along with the elect of Jacob's seed, over whom the LORD invoked His own New Man name and gave to Jacob/Israel's seed his Living Oracles....
We Gentiles get in on the promises in this age of the Church, but after we are removed from the earth, the Glory goes with us, the Church [the praying and watching Church] and the Glory does not return until He returns in the Person of God the Son, who enters the Millennial Temple in Jerusalem, as pr Ezekiel.
Paul was teaching from the Law and the prophets, where God Himself taught that the circumcision of the heart was what counted, and outward show counted for naught and he that did not keep His Law would be cut off from Israel -Did you not know that? -for his heart was in unbelief.
Deu 30:6 And the LORD thy God will circumcise thine heart, and the heart of thy seed, to love the LORD thy God with all thine heart, and with all thy soul, that thou mayest live.
Jer 4:4 Circumcise yourselves to the LORD, and take away the foreskins of your heart, ye men of Judah and inhabitants of Jerusalem: lest my fury come forth like fire, and burn that none can quench it, because of the evil of your doings.
Eze 11:19 And I will give them one heart, and I will put a new spirit within you; and I will take the stony heart out of their flesh, and will give them an heart of flesh:
Eze 36:26 A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.
The end goal of the Law is Christ....
Paul taught nothing new. He only spoke from what was already written, as Jesus Himself did when He walked the earth in His Jewish, New Man, flesh.
Jesus still is a Jew, as Paul is, by natural birth. Paul was not cut off from the natural Tree, "Israel", as an unbelieving branch when the Messiah revealed Himself to him, but He embraced His Messiah, and was, as He said, a Jew of Jews.