Paul, writing by inspiration of the Holy Spirit, wrote the letter of Romans to “all who are in Rome” (Romans 1:7). These people were Christians, “the called of Jesus Christ” (Romans 1:6).
What do we know about the Lord’s church in Rome when this letter was written?
There were several house churches.
There were at least three different “house churches” where the Christians met in Rome.
The house of Priscilla and Aquila (Romans 16:3-5).
The house of Asyncritus, Phlegon, Hermas, Patrobas, and Hermes (Romans 16:14).
The house of Philologus and Julia, Nereus and his sister, and Olympas (Romans 16:15).
All of these people were Christians. For whatever reason, they were spread out in various meeting places.
While Romans does seem to indicate some friction between the Christians in Rome (mainly between Gentiles and Jews), the church does not appear to be divided. Had they been divided, Paul likely would have addressed them in a much firmer way - much like he did with the church in Corinth (1 and 2 Corinthians).
From the description given in Romans 14 and 15, a large amount of social interaction existed in the Roman church between the groups. Further, Paul addressed his letter to the whole church, calling them “beloved of God” and the “called.” - Pollard, Truth for Today Commentary, 14
Christianity likely came to Rome by Jewish people.
Acts 2:10 shows that there were Jews and/or Gentile converts to Judaism in Jerusalem from Rome on the Day of Pentecost when Peter and the rest of the apostles proclaimed Jesus as the Lord and Christ (Acts 2:36).
Some of these people probably traveled back to Rome and began proclaiming the gospel of Christ (Mark 16:15-16).
It is likely, therefore, that the Roman church began with a heavy Jewish overlay, which stressed ancestral customs, feast days, food laws, and especially the Law. As such, its earliest days can be characterized as a “Judaizing” type of Christianity. - Pollard, Truth for Today Commentary, 15
By the time Paul wrote to the church in Rome, the church was made up of mostly Gentiles, while there were still some Jewish people like Aquila and Priscilla (Romans 16:3).
The event that shaped the church in Rome and set the stage for the letter of Romans.
The edict of Claudius in A.D. 49 banished the Jews from Rome. This would have included all Jewish people who were Christians as well.
After these things Paul departed from Athens and went to Corinth. And he found a certain Jew named Aquila, born in Pontus, who had recently come from Italy with his wife Priscilla (because Claudius had commanded all the Jews to depart from Rome); and he came to them. (Acts 18:1-2)
The ban was lifted when Claudius died in A.D. 54, and Jews were free to return to their homes and lives in Rome.
After an absence of five years, the returning Jewish Christians found a different church from the church they knew when they left. Now it was composed of a Gentile majority. Instead of Jewish leaders and Jewish customs being predominant, now the emphasis was elsewhere, setting up a different dynamic leading to conflict in some cases. - Pollard, Truth for Today Commentary, 17-18
Paul commends the Christians in Rome for their faith that is “spoken of throughout the whole world” (Romans 1:8). While some tension did exist, there appears to have been far more good than bad.
To address some of the underlying tension between Gentiles and Jews, Paul wrote the letter of Romans to emphasize and dig deep into the gospel of Jesus Christ (Romans 1:16-17).
When congregations of the Lord’s church experience tension - perhaps between young and old, black and white, or cultural differences - we would do well to consider the gospel of Christ at a much deeper level. It’s the approach the Holy Spirit took through Paul to the church in Rome. It will still work today.
The Catholic Church is indefectable. The Catholic Church , in Her teaching, Worship... Holy Sacrifice of the Mass...cannot change in Her essence. So the Church in Rome, the Catholic Church, looks like Catholic Church which is a remnant, virtually no property, no pope, hidden
Interesting: this is how Catholics knew there was another Church that started with John XXIII
https://m.youtube.com/watch?v=wcvfe4zJ-TQ