Judaism is at our roots. It is the ladder by which we are brought up into the promise of Jesus Christ. Don't neglect your Old Testament. Don't look down upon the Israel of God. Don't think you can stand in your Christianity apart from the undergirding and the promises God gave and will keep to all of Israel. The Gentile believers Paul was writing to could not trace the faithfulness of God through their own fathers who were pagans. And so, they may have felt as if they stood out as singly the people who have been birthed by God. Paul tells them, you are here because of God's faithfulness to the Jewish fathers and his promises to them. Don't boast over them be humble.