Christianity came to Rome through the Synagogue, likely from Jews who heard the gospel while in Jerusalem as early as Pentecost. Paul wrote Romans in the second half of the 50s to already existing congregations which have separated from the synagogues or were formed outside of the synagogues of Rome.
Jewish population Rome began as early as the Hasmonean delegation to Rome in 161 B.C.E, but grew rapidly after 63 B.C.E., many Jews prospered and gained freedom and citizenship. They were located in the Transtiberinum, Campus Martius, the Suburba, and Ostia (Rome’s port-city) by the first century.
Thirteen synagogues (five for certain, eight debated based on inscriptions) have been identified from the second and third centuries B.C.E., named for the most part after persons or the location, such as Augustus or Agrippa, possibly the Herodians. Synagogues were small ethnic enclaves and collegia organizations. Evidence for the church developing out of the synagogue is found in Romans 16. Aquila and Priscilla are Jewish, as well as Andronicus, Junian and Herodion who are identified as Jewish (7, 11), the names Mary and Aristobolus may also indicate a Jewish origin.
According to Acts 18:2 and Suetonius (Claudius 25.4) Jews were expelled from Rome in A.D. 49 (although Dio Cassius dates the edict of Claudius to A.D. 41). Just who was expelled is debated. It is hardly all Jews were expelled given the population of Jews in Rome It seems likely those thought to be the ringleaders causing the riots were expelled, which would be the Jewish Christian evangelists. It is certain that by A.D. 49 there were potentially violent debates among Jews over who Jesus was. These disturbances were bad enough to attract the attention of the authorities, similar to Paul in Philippi and Thessalonica.
How many congregations of Christians existed in the mid-50s can be determined from the names in Romans 16. Peter Lampe argues for at least five different Christian “islands,” possibly as many as many as eight. For example, in Rom 16:3-5 Pricilla and Aquila are greeted along with those in the church which meets in their house (τὴν κατʼ οἶκον αὐτῶν ἐκκλησίαν). There are other Christian names listed who probably did not belong to the same congregation (or they would be listed with the others), so at least two more churches could be implied.
What does this mean for reading Romans? The Christians in Rome have been preaching Jesus as Messiah for many years before Paul wrote to them and they have suffered for the message of a crucified Messiah. Even if there are ten congregations in Rome, and even if there are 50 members of those ten congregations, there are only 500 believers in the largest city in the Empire. Christians are meeting in small locations (homes, workshops, etc.) and are a tiny minority in the city.
Paul is therefore writing this presentation of the Gospel to congregations who need to be reassured the Gospel of Jesus Christ in the face of potential isolation and persecution. Romans presents Paul’s Gospel of the grace of God in a clear way in order to encourage these congregations. What specifically in Romans might speak to the situation of these tiny islands of Christianity?
Bibliography: Peter Lampe, From Paul to Valentinius. Minneapolis: Fortress Press, 2003.