Paul loved the Jews probably more than any other Christian writer throughout history. His life consisted of many paradoxes. He hated Christians and loved the Jews, then became one of the chiefest of the Christians. Most of the Jews hated and hunted him for this turn but his love for his true and pure heritage never waned.
Yes, and interestingly enough, Paul was a Benjamite. Benjamin was Joseph’s full brother, both born of Rachel. Ephraim, Joseph’s son, was the namesake and ruler class of The Northern Kingdom, which was dispersed and lost. (Judah Jews were dispersed, but not lost.) Paul may not of realized it, but he may have been going out and gathering in his brethren, who chief among them was Ephraim.