What does Romans 15:12 mean?
Paul is offering quotations from Old Testament Scriptures to support his recent claim. He is teaching that God's plan all along, has been for both the Jews and the Gentiles to come to faith in Christ. Those prophecies may not have explicitly spelled out how this would come to pass, but Paul is eager for his readers to see that the prophecies always pointed to the inclusion of the Gentiles in the praise of God.Now Paul refers to something written by the prophet Isaiah in a version of Isaiah 11:10–12. "The root of Jesse" refers to the descendant of Jesse who will rise to rule over Israel and all the Gentile nations. This is a prophecy about the coming of Israel's promised Messiah. The Gentiles, however, will not merely become the servants of the Messiah. The verse ends with the statement that they will hope in Him.
Paul is connecting that Scripture to the truth that Christ has become Lord of all peoples, and the Gentiles who come to God through faith in Christ have placed their hope in Him for their salvation. Paul's bottom line is that Jesus is the fulfillment of all these Old Testament writings both for Israel and for the Gentile nations (Galatians 3:28–29).