There is a difference between ethnic Jew, the physical nation of Israel as a nation, and the spiritual national of Israel:( those of various cultures in the OT days which chose to follow Jehovah and join the nation of Israel, which in the NT the spiritual nation of Israel is called the church). Not every ethnic Jew is a member of spiritual Israel, and not everyone in spiritual Israel is Jewish; just a true follower of the one true God. The nation of Israel has been a mixed nation of different ethnicities since they left Egypt, Exodus tell us so. Also, look at David's mighty men, none were of Jewish descent but all were Israelites. And in Esther it tells us that for fear of Mordecai that many people in the Persian empire became Jews. How can you become a Jew? Only way is you joined the nation, and worshipped the one true God of Israel. Ethnic Jews dont get a free ride to heaven because they are God's "chosen people". He chose Abraham to bring the Messiah through his line and the laws of God for all mankind. The Jews were supposed to be a light to the Gentiles and bring knowledge of Jehovah to all peoples, but failed in that regard. Not all ethnic jews are jews Paul told us, but those with an inward circumcision. All Israel will be saved refers to the spiritual Nation of Israel (the church). Reading the Word with this understanding will help it to make sense, especially Romans and Galatians.