I'm not arguing that faith is not required and that the true Israel are those who were not only born in the lineage of Jacob but had faith in their Messiah. In Galatians the gentiles didn’t want to become physical Jews per se but were told they had to be circumcisied to be saved by the false teachers.
So don't worry, I'm not into a legalistic Judaism even though I believe God will be dealing with them directly in the near future.
Paul says trust Christ alone, His work alone and do not put your faith in works [religious exclusivism] such as circumcision, Law etc. He talks about the Jews and their ethnical pride. And then He continues "is God only the God of the Jews?". No, His people are now all who believe in Christ.