Whilst it is questionable that Peter made it to Rome, a church was established there before AD 70. ( One of the Christ-mythists argues that a church was established there circa 40 AD.)
xan
jonathon
Paul’s letter to the Romans was written to the Church at Rome. At the time of this letter, the Church at Rome was already established. Such that the Faith of the Roman Church was already heard all over the world
Rm 1:
7* To all God’s beloved in Rome, who are called to be saints: Grace to you and peace from God our Father and the Lord Jesus Christ. 8* First, I thank my God through Jesus Christ for all of you, because your faith is proclaimed in all the world. 9 For God is my witness, whom I serve with my spirit in the gospel of his Son, that without ceasing I mention you always in my prayers, 10* asking that somehow by God’s will I may now at last succeed in coming to you. 11 For I long to see you, that I may impart to you some spiritual gift to strengthen you, 12 that is, that we may be mutually encouraged by each other’s faith, both yours and mine. 13* I want you to know, brethren, that I have often intended to come to you (but thus far have been prevented
In closing, Paul warns them about the evils of division. Those who break from this Church don’t serve God but their own bellies.
Rm 16:
17* I appeal to you, brethren, to take note of those who create dissensions and difficulties, in opposition to the doctrine which you have been taught; avoid them. 18 For such persons do not serve our Lord Christ, but their own appetites, * and by fair and flattering words they deceive the hearts of the simple-minded. 19* For while your obedience is known to all, so that I rejoice over you, I would have you wise as to what is good and guileless as to what is evil; 20* then the God of peace will soon crush Satan under your feet.
.