The apostle sums up what he had taught, especially the gospel of the nations. Christ ‘was a minister of the circumcision for the truth of God, to confirm the promises made to the fathers’ (v.8), but the nations had no such promises – they had to glorify God for His pure mercy. Because they had rejected Christ, the Jews also had to depend on God’s pure mercy. Paul quotes from the Old Testament, showing that this mercy to the nations was always contemplated by God – there should be a root of Jesse to reign over the nations and their hope should be in Him. (See v.12, Isa 11:10, Matt 12:21). He rests on the word hope. ‘Now the God of hope fill you with all joy and peace in believing, that ye may abound in hope through the power of the Holy Ghost” (v.13). Such is the Christian’s joy and peace in believing, that his spirit rises in hope, trusting in God, and looking forward to the blessed time when all shall be accomplished in light – when he will be with Jesus.
Paul now refers to the public ministry that had been confided to him by Jesus Christ. He wrote to the saints in Rome as a minister of the gospel of God to the Gentiles. He presents himself figuratively as a priest (a minister), so that he could offer up the Gentile Christians to God, consecrated, sanctified to God by the Holy Spirit. He shows how he had laboured in power, and how he had not gone where Christianity was already established, but to poor souls far away from God and light. Now this ministry was closed.
Paul had finished his service in Asia and the Greek speaking world, having laid the foundation, preaching in spite of the dangers, where no one else had. He had formed and taught assemblies from Jerusalem to Illyricum, so now they could resist evil and false doctrine. The Greek world was Christianised: others might build, but Paul’s work was done. He had learnt to work wherever God called him to do so. Now the Latin world was before him, starting with Rome.
But now he was going to Jerusalem to minister to the saints. His apostolic ministry finished, he undertakes a diaconal service to Jerusalem. He certainly did not fulfill his mission as intended (See v.31). Indeed his fears as to what might happen in Judaea are stated in verses 30-32 [and more so in Acts 20:22].
God would not allow Latin Christianity to have an apostolic foundation. There were already Christians in Rome. We do not know who founded the Roman assembly – there is no evidence that it was Peter. There had been no wise master-builder: Christianity founded itself there. He came to Rome as a prisoner after two years’ captivity in Caesarea; then he remained two years captive in his own house in Rome. Now the history closes.
As far as we know Paul never went to Spain. Subsequent history may be inferred from 2 Timothy and other scriptures. This in no way affects the moral or ecclesiastical bearing of any of the epistles.
The close of Paul’s service is deeply affecting. He was so like his Master, though at a distance. He had worked with energy and exercise. There were failures because of the materials with which he, like the Lord had to use. Nevertheless, despite the materials, God’s ultimate purpose was accomplished. Compare Rom 15 with Acts 20:29-33 and Isaiah 49:4-6.
In the providence of God’s ordered path, Paul witnessed to all the authorities from the Sanhedrim to the Emperor, and the Lord’s grace sustained him in it. His apostolic service was to close in unwilling captivity, and Paul is delivered by the Jews to the Gentiles to suffer in grace, like his Lord, at their hands. Of course, Paul did not face it perfectly like the Lord Himself: He did so in the calmness of unvarying perfection, drinking the cup none else could, and that, if it could be, was more perfect than anything.
A simplified summary of part of the introduction to John Nelson Darby’s Exposition of the Epistle to the Romans