Who was the leader of Christian faith in Rome?

Answer 1

If you mean the ancient city of Rome, it has always been the Bishop of Rome, (the title of Pope was added later). In the Roman days he was the leader of what was called Latin or Western Christianity (now it is called Catholic Christianity). If you are referring to the Roman Empire, there were five leaders of Christianity, the patriarchs. One of them was the Bishop of Rome. The others were the patriarchs of what was then called Greek or Eastern Christianity (now it is called Orthodox Christianity). They were the patriarchs of Constantinople, Antioch, Jerusalem and Alexandria.