In the past, it only matters to whom one was related to Abraham, because God made the earthy promise to him about his children and grandchildren and great grandchildren, etc. It was to them, the blood related to Abraham and to those who got circumcised and obeyed the old law.
But, the new covenant gospel was told to Abraham that would come in the future, about a people who would have a better country, a spiritual, heavenly country, a people who would belong to God because of FAITH, faith like that of Abraham.
The Jews who were blood related but who did not have faith, they were cut off and condemned, they were children of the devil, they were children of wrath. Those Jews were put to the same place as all the Gentiles were.
The only thing that will save anyone, anyone from any nation and ethnicity would be to turn to God in faith in His Son and repent of sins, obey His Son's teachings.
When Jesus comes again, it will be too late to repent of sins because he is not coming to bear sin, he is coming for those waiting for him. One must know Him by obeying Him. One must already be saved by the time he comes again.