The idea that only those of the hebrew lineage can be saved has been disproved through.
Rev 7:9 After this I beheld, and, lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues, stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;
Rev 7:10 And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
Not too mention any foreigner could become an Israelite in the Old Testament(Exodus 12:48-49).
Anyone who has truly been saved by the grace of God has had their heart changed by the holy spirit. Thats why Paul alluded to the futility of being changed and renewed by the holy spirit and then going back to the law. One cant just choose which parts of the law they can keep. They have to keep the whole law and its written that anyone who stumbles in one area of the law has broken the entirety of it. You cant be righteous before God in the law. Only someone who is guilty. I promise you that if you went to God under the impression that you keep the law and asked him to reveal to you sin in your life and thoughts that you still cling to it would overwhelm you to how big of a sinner you still are.