Actually, while I support Vladimir's "bigger picture," a minor tweak need to be made, for the sake of accuracy:
The term "Roman Catholic" is certainly often used to emphasize Rome and make whore-of-Babylon connections by Protestants. However, the term does predate the Reformation. It was said within the Roman Empire that the whole of the civilized world was Roman; what was not Roman was Barbarian. Hence, Roman came to mean "civilized." It was used as a modifier to the term "Catholic" to recognize that there were pagan heathen who did not know of Christ.
"Roman" does not mean "of the city of Rome." In fact, the Pope lives in exile FROM the city of Rome, across the Tiber, in the Vatican City. This makes the expression "crossing the Tiber," highly ironic, since on one side of the Tiber is the Catholic Church, and on the other side is the City of Rome, plausibly labelled "the Whore of Babylon." Hence, someone "crossing the Tiber" is leaving the Whore of Babylon to join the Catholic Church. :^D
Alternatively, "crossing the Tiber" could mean leaving the Catholic Church to join the Whore of Babylon ... I'm thinking of a certian Matthew Fox, for example ....
This is a minor point, but....The term "Roman Catholic" was NOT used before the Reformation in english. You are referring to it in what could only be a Latin form that was more grammatical error than expression of anything. You would be hard pressed to come up with more than three times it was ever used in Latin before the Reformation. As we use it today, it is an English language term, created in the sixteenth century by Anglicans.