As Paul goes on to state the purpose of his apostleship, he discloses further aspects of the gospel.
The scope of the gospel is all the nations. Paul defines its scope as “all the Gentiles.” This seems to imply that the Christians in Rome were predominantly Gentile. Paul affirms that the gospel is for everybody; its scope is universal. Paul himself was a patriotic Jew who retained his love for his people and longed passionately for their salvation. At the same time, he had been called to be the apostle to the Gentiles. If we are to be committed to world mission, we too will have to be liberated from all pride of race, nation, tribe, caste and class, and acknowledge that God’s gospel is for everybody, without exception and without distinction. This is a major theme of Romans.
The purpose of the gospel is the obedience of faith. In Romans, Paul insists more strongly than anywhere else that justification is through faith alone. Yet here he apparently writes that it is not by faith alone, but by obedience. Does the apostle contradict himself? No, we must give him credit for consistency of thought. This is the obedience that comes from faith, not the obedience of law. The proper response to the gospel is faith, indeed faith alone. Yet a true and living faith in Jesus Christ includes an element of submission (especially because its object is “Jesus Christ our Lord” [v. 4] or “the Lord Jesus Christ” [v. 7]) and leads inevitably into a lifetime of obedience.
Why did Paul desire to bring the nations to the obedience of faith? It was for the sake of the glory and honor of Christ’s name. The highest of all missionary motives is neither obedience to the Great Commission (important as that is) nor love for sinners who are alienated and perishing (strong as that incentive is, especially when we contemplate the wrath of God), but burning and passionate zeal for the glory of Jesus Christ. Before this supreme goal of the Christian mission, all unworthy motives wither and die.
From Reading Romans with John Stott by John Stott with Dale and Sandy Larsen.