It was prophesied that Gentiles would be called by the name Israel, foretelling the inclusion of the them into Elect Israel Isa 44:5
5 One shall say, I am the Lord's; and another shall call himself by the name of Jacob; and another shall subscribe with his hand unto the Lord, and surname himself by the name of Israel.
This is the fulfillment of the Abrahamic Promises to include Gen 12:3
3 And I will bless them that bless thee, and curse him that curseth thee: and in thee shall all families of the earth be blessed.
This is linked to Isa 44:1-4
Yet now hear, O Jacob my servant; and Israel, whom I have chosen:
2 Thus saith the Lord that made thee, and formed thee from the womb, which will help thee; Fear not, O Jacob, my servant; and thou, Jesurun, whom I have chosen.
3 For I will pour water upon him that is thirsty, and floods upon the dry ground: I will pour my spirit upon thy seed, and my blessing upon thine offspring:
4 And they shall spring up as among the grass, as willows by the water courses.
That's why the Spirit came as the blessing of Abraham upon the Gentiles Gal 3:13-14
13 Christ hath redeemed us from the curse of the law, being made a curse for us: for it is written, Cursed is every one that hangeth on a tree:
14 That the blessing of Abraham might come on the Gentiles through Jesus Christ; that we might receive the promise of the Spirit through faith.
So Gentiles can call themselves Israel as Per Isa 44:5
5 One shall say, I am the Lord's; and another shall call himself by the name of Jacob; and another shall subscribe with his hand unto the Lord, and surname himself by the name of Israel.
This is a Spiritual reality, nothing to do with the natural. 9
We are Christians, not Jews; we are spiritual Jews only. We are heirs to Abraham through Christ, IF we follow Him and do what He commands.
We can’t be Jews, we are no longer under Law. There are no Jews, nor Greeks, but all are one under Christ.