even us whom he has called, not from the Jews only but also from the Gentiles? (ESV)
There is nothing greater than God himself. There is also nothing more important than God getting glory. God has called people unto himself. Why are they called? To give him glory. The Jews had known for many centuries that they were called by God. They even knew that they were called by God to give glory to God.
Paul challenges them with something else. He is telling him that not only have the Jews been called by God for his glory, but so also from the Gentiles he has called men and women unto himself so that they would give him glory. This thought would have been repugnant to the Jews who viewed all Gentiles as vile and referred to them as dogs.
If we truly understand this relationship of Jews and Gentiles it makes sense out of the Apostle Paul's treatment by the Jews. When Paul began his ministry he would go into every town and preach the Gospel, first to the Jews, and then to the Gentiles. The idea that the Gentiles were to be offered the same Gospel that was preached to the Jews was controversial and highly offensive.
God has called people from every tribe and nation unto himself. Out of his great love for mankind he has made a way for people to be made right with him through the sacrifice of Jesus Christ, God's son. Jews may be jealous of the offer of salvation being made to Gentiles, but that will not hinder God's offer of salvation to all peoples.
Give God glory. There is nothing greater that you can do. If you are a Jew or a Gentile you have the privilege and opportunity to praise your Creator. He is glorious and worthy to be praised. He is calling people from every tribe and people of Earth.