The ancient city of Rome had a Jewish population almost equal to Jerusalem’s. The emperor Pompey brought large numbers of Jews to Rome as slaves. Emperor Claudius’s later treatment of the Jews is a study in contradictions. First, he granted Jews the freedom to worship and gave them rights as citizens. But, unfortunately, his kindness did not continue. According to the historian Suetonius in his The Life of Claudius, the Jews were expelled in AD 49 because they “constantly made disturbances at the instigation of Chrestus.”
Chrestus is likely a mispronunciation of Christ. During Claudius’s reign, the gospel came to Rome. Many Jews became believers in Jesus as the Christ. Many did not. Those who rejected Jesus as the Christ began to riot against those who did. Claudius’s solution to this social unrest was to expel all the Jews. The book of Acts notes this historical fact in a passing comment about Aquila and Priscilla, who had recently come from Rome “because Claudius had commanded all the Jews to depart from Rome” (Acts 18:2).
Claudius’s expulsion of the Jews from Rome would have dramatically altered the cultural feel of the local churches in Rome. These churches were founded by Jewish converts to Jesus and would have had a distinctly Jewish cultural feel. Greeks who became believers in Jesus were assimilated into these Jewish churches. With the expulsion of the Jews from Rome, these congregations that were once culturally Jewish would have begun to take on a decidedly different cultural feel.
When Claudius died in AD 54, the decree prohibiting Jews from living in Rome died with him. Jews were now free to return, and many did. When they came back to Rome, they would have been shocked. Their churches had changed, and these changes didn’t sit well with them. They began quarreling over their differing opinions (Romans 14:1).
This social and cultural dynamic is one of the reasons for Paul’s reference to the Jew first and also for the Greek in Romans 1:16. This refrain is repeated frequently (Romans 2:9–11; 3:21–24, 28–30; 4:3–16; 9:8, 22–33; 10:11–13; 11:32; 15:7–12; 16:25–27). The repetition of these phrases was not a rhetorical flourish to make the letter sound good. It goes to the heart of what Paul was trying to accomplish by writing this letter. Through the truth of the gospel, Paul is trying to facilitate a social context that would foster unity between Jews and Greeks.
The gospel recognizes the universality of the problem of sin and the promise of salvation. God’s wrath is against all ungodliness and unrighteousness (Romans 1:18), not just that of those we tend to despise. Both Jews and Greeks are under sin (Romans 3:9). The gospel is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek (Romans 3:16). Our solidarity in sin and the believer’s solidarity in the gospel has the power to unite a church no matter our cultural differences.
 Suetonius, The Lives of the Twelve Caesars: The Life of Claudius, 25:4, http://penelope.uchicago.edu/Thayer/E/Roman/Texts/...