Toward the end of his 3 year ministry in Ephesus on his third missionary journey Paul wrote 1 Corinthians before traveling north to Troas and then on to Macedonia, visiting and strengthening the churches he had established there on his second missionary journey. From Macedonia he wrote 2 Corinthians to prepare the believers there in Achaia for his imminent arrival, for a minority persisted in opposing him and it was not at all his wish to have to wield his apostolic authority with the exercise of church discipline. Those opposing his authority were not unlike so many others Paul had repeatedly encountered over the course of his ministry during the past 13 years: they were Jews, even Jews who supposed themselves to follow Christ (2 Cor 11:13,22), but who could not fully accept nor understand how God’s salvation could really be a free gift apart from obeying the law of Moses. They had opposed him nearly everywhere he went: Antioch (Gal 2:4), Galatia (Gal 3:1-2), Thessalonica (Acts 17:5), Berea (Acts 17:13), Ephesus (Acts 21:27, 24:18), and Corinth. And everywhere he went he was confronted with many of the same questions: God gave His great and glorious Law to the Jews; do not the Scriptures teach that they are saved by obeying it, and if the Gentiles are to be saved, don’t they have to obey it as well? If one is justified apart from the Law, then what is its purpose, and what advantage is there to being a Jew? How can one really be justified entirely by grace through faith? Wouldn’t that nullify the very law that defines righteousness and actually lead people into sin? And if in fact the gospel is true, isn’t it contrary to the many promises of God concerning the Jews since the great majority of them are rejecting it?
As a result of his continual defense against this opposition to the gospel Paul had developed a deep understanding of its truths and their significance to the Church. At its founding on the day of Pentecost the first believers, including the original apostles, could hardly imagine the immense theological implications of Christ’s death and resurrection to their understanding of God’s law and how it relates to the Gentiles for whom Christ also died. They understood and accepted Jesus as their promised Messiah who had died and risen again to save them from their sins; but they had not yet reasoned to understand that the efficacy of that salvation came from reckoning themselves dead in Christ, which necessarily meant that they were also dead to the Law. Because of his unique calling as the apostle to the Gentiles Paul was given special insight into this truth (see Eph 3:2-12), and as a result of the prolonged opposition to his ministry he had honed his defense of it.
Now, having established the gospel in the eastern portion of the Roman empire, and “with no further place for me in these regions” (Rom 15:23) Paul turned his attention westward. His desire was to go to Spain (Rom 15:24), and as Antioch had been his home base for the eastern campaign, he knew Rome itself would be a strategic center for a western campaign. However, while Paul “had for many years a longing to come to you” he had never been to Rome, and the church there was already well established, probably by converts from the day of Pentecost, although the apostle had no doubt already influenced the church through his many contacts there whom he greets in chapter 16.
Thus as Paul wintered in Corinth at the end of his third missionary journey he was already laying the foundation for his future missionary endeavors. As the apostle to the Gentiles it was important for his influence to be personally felt in the Roman capitol of the Gentile world. He also knew that the opposition he had faced from the Judaizers in the east would no doubt confront the Roman church as well (see Rom 16:17-20). Thus in this letter Paul is both bracing the Romans against the influence of the Judaizers with a systematic understanding of the great truths of the gospel he had acquired over the course of his ministry, while at the same time preparing them for an anticipated future visit in which he hopes to be helped on by them in his missionary endeavors westward.
Interestingly, whereas 2 Corinthians was written just a few months previous and is probably Paul’s least systematic epistle, Romans is without doubt his most systematic, following a definite structure that is easily outlined: Introduction (Rom 1:1-17); Condemnation: all mankind is guilty of sin and under God’s wrath (Rom 1:18-3:20), including not only the Gentiles (Rom 1:18-32) but also the Jews (Rom 2:1-3:20); Justification: righteousness comes through faith apart from the law (Rom 3:21-5:21); Sanctification: in answer to the objection that the gospel allows people to continue in sin if salvation is by faith and not by obeying the law (Rom 6-8); Vindication: in answer to the charge that if the gospel is true, God’s promises to Israel have failed since so many Jews have rejected the gospel (Rom 9-11); Application: practical results of the gospel for Christian living (Rom 12:1-15:13); Conclusion (Rom 15:14-16:27).