Here’s something that many people I talk to about Paul’s Letter to the Romans don’t seem yet to have grasped. The earliest house churches in Rome would have been primarily Jewish and would have culturally felt Jewish, but in A.D. 49 the Roman Emperor Claudius kicked the Jews out of Rome. Jewish Christians, of course, would have been expelled along with the rest of the Jews. During the five years between Claudius’s edict (A.D. 49) and his death (A.D. 54) when the edict lapsed and Jews started to return, the composition and self-understanding of the house churches in Rome would have shifted considerably. Paul’s letter to the Romans would have arrived in Rome somewhere around A.D. 57, during the period when Jews were still trickling back into Rome. If you can fix in your mind that the expulsion of Jews from Rome had a tremendous impact on the churches in that city, you will understand the message of Romans oh-so-much better!
James C. Walters in Ethnic Issues in Paul’s Letter to the Romans: Changing Self-Definitions in Earliest Roman Christianity lists the three most important effects that the expulsion of Jews and their subsequent return would have had on the Roman churches.
1. Persons expelled from Rome: The most obvious effect is that the persons who comprised the churches would have been substantially altered. The Gentiles who remained would have begun meeting together without Jewish leadership and input, and those they reached with the good news of Christ during the intervening five years would have been Gentiles. When Jewish Christians began returning five years later, they would have encountered house churches composed of more Gentiles than Jews.
2. Jewish and Christian Self-Definition: The edict to expel Jews also would have pushed the returning non-Christian Jewish community and the already-present house churches to self-define in relation to one another. Before the edict, the ruling Romans would have viewed Christians as a subset of Judaism—the churches, after all, were socialized like Jewish groups. But after the edict and the changing socialization of the groups into Gentile-ish communities, the process of viewing Jews and Christians as separate groups would have sped up (both as viewed from the inside [emic perspective] and as viewed from the outside [etic perspective]). Note that by A.D. 64—only seven or so years after Paul’s letter arrived, this process would have been complete; Christians were successfully identified as a group separate from the Jews as Nero’s soldiers carried out their brutal persecution of Christians in Rome. Paul’s letter arrived while this process of changing self-identification was taking place. Jewish Christians coming back to Rome had to struggle with the question of whether they were primarily Jewish or whether they were primarily Christian (which would have felt increasingly like a Gentile thing to them).
This scenario is strengthened if we read the Roman historian Suetonius to mean that the Jews were kicked out of Rome because of disturbances caused by disagreements between non-Christian Jews and Christian Jews (all were simply “Jews” in the Roman mind before Claudius’s edict of expulsion). The returning non-Christian Jews no doubt would have wanted to keep their distance from the Christian Jews after they returned to Rome to avoid further conflict with the Roman authorities. Furthermore, when they learned that Christian groups were now socially dominated by Gentiles, this would have confirmed in their minds that separation was necessary.
3. The Unity of Christianity in Rome: Upon their return to Rome, Jewish Christians would have been placed in the awkward situation of having to assimilate into groups that felt rather foreign to them. This is a reverse of what would have happened before Claudius’s edict; at that time Gentiles would have had to adapt to Jewish customs to fit in. Surely, when the Jewish Christians showed up again in the now mostly-Gentile churches, tensions would have emerged over who was in charge and how Christians were supposed to relate to all-things-Jewish.
If this reconstruction is correct—and it does seem to be where the external historical evidence leads us—then we should expect to encounter evidence within the book of Romans that questions of self-identification of Jewish and Gentile Christians were in Paul’s mind as he wrote the letter. This is in fact one of the things we discover when we read it with some historical awareness. Knowing this background will cause you to be more attentive to such questions of Jewish-Christian and Gentile-Christian self-identification when you open Paul’s famous letter.
One of Paul’s teaching strategies in his letter to the Romans is to use questions (85 at my count) to move along his argument and to help his readers think hard about what he’s writing. I’ll close this post with 15 of Paul’s questions that will underscore that Paul was speaking into just such a historical situation as I’ve described here. Notice that the self-identification of Jewish and Gentile Christians vis-à-vis one another and in relation to the non-Christian Jewish community plays an important role in this list of questions. As you keep the historical setting in mind, you’ll become a much better reader of Paul’s letter to the Romans.
3:1 Then what advantage has the Jew? Or what is the benefit of circumcision?
3:9 What then? Are we better than they? Not at all; for we have already charged that both Jews and Greeks are all under sin;
3:29 Or is God the God of Jews only? Is He not the God of Gentiles also?
3:31 Do we then nullify the Law through faith? May it never be! On the contrary, we establish the Law.
4:1 What then shall we say that Abraham, our forefather according to the flesh, has found?
4:9 Is this blessing then on the circumcised, or on the uncircumcised also?
7:1 Or do you not know, brethren (for I am speaking to those who know the law), that the law has jurisdiction over a person as long as he lives?
9:30 What shall we say then? That Gentiles, who did not pursue righteousness, attained righteousness, even the righteousness which is by faith…
10:18 But I say, surely they have never heard, have they?
10:19 But I say, surely Israel did not know, did they?
11:1 I say then, God has not rejected His people, has He?
11:2 Or do you not know what the Scripture says in the passage about Elijah, how he pleads with God against Israel?
11:11 I say then, they did not stumble so as to fall, did they? May it never be! But by their transgression salvation has come to the Gentiles, to make them jealous.
11:24 For if you were cut off from what is by nature a wild olive tree, and were grafted contrary to nature into a cultivated olive tree, how much more will these who are the natural branches be grafted into their own olive tree?
14:10 But you, why do you judge your brother? Or you again, why do you regard your brother with contempt?
 Suetonius, Claudius 25.4. This expulsion of Jews from Rome is confirmed by Acts 18:1-2, “After these things he [Paul] left Athens and went to Corinth. And he found a Jew named Aquila, a native of Pontus, having recently come from Italy with his wife Priscilla, because Claudius had commanded all the Jews to leave Rome.”
 Along with any Gentiles who had been socialized as Jews and thus viewed as Jewish proselytes by the Roman authority. See James C. Walters, Ethnic Issues in Paul’s Letter to the Romans: Changing Self-Definitions in Earliest Romans Christianity (Valley Forge: Trinity Press International, 1993),
 Ibid., 56-64.
 “Since the Jews were constantly rioting under the leadership of Chrestus, he [Claudius] expelled them from Rome.” Seutonius, Lives of the Twelve Caesars, (Claudius 25.4) cited in Robert M. Grant, Second Century Christianity: A Collection of Fragments, 2nd ed. (Louisville: Westminster John Knox Press, 2003), 7. (In Latin: Iudaeos impulsore Chresto assidue tumultuantis Roma expulit.) Many historians suggest that although Suetonius (writing about A.D. 120) thought someone named Chrestus (a common Roman name) had caused the disturbances, the disturbance that led to the explusion of Jews was in fact over one named Christus (Christ), thus a disturbance between non-Christian Jews and Christian Jews.