The Apostle Paul was addressed in three ways 1. As a Hebrew. As an Israelite. As a Jew. Obviously, Paul recognized no such distinctions as invented by this theory.
All terms interchange.
No, for the scriptures are plain that Christ was the promised Messiah for all Israel. Again, the terms interchange. We would expect, if the theory is correct, that the English coronation stone could be analyzed and found to be of the type found in Israel. Rather it is a theory that cannot stand up to Biblical or scientific examination. It should be rejected by those professing Christianity.