Catholic Church, the Whore of Babylon
Judging by the criteria of biblical literalism it is certain that there is no mention of the Catholic Church in the book of Revelation as the Whore of Babylon. By contortions of interpretation some groups and individuals equate the Whore in Revelation 17:9 with the Catholic Church, since Rome is the famous city on seven hills, and the Church's principal See is Rome. This position is untenable, both factually and from the only words of Scripture which tell us of the actual doctrine of the Antichrist, those of the Apostle John in his letters.
There would seem to be two choices, either interpret Rev 17:9 absolutely literally or according to some interpretive key that is metaphorical, allegorical or otherwise non-literal. Lets look first at literal interpretation.
"The seven heads represent seven hills on which the woman sits."
First of all, no Pope has ever lived or had his "seat" (cathedra, See) on any of the seven hills of Rome. These hills are small hillocks (Capitoline, Palatine, Esquiline, Aventine and three lesser "bumps" in central Rome) where the religion and government of pagan Rome was situated. The Catholic Church's headquarters at the Lateran (the cathedral) and at the Vatican (where the Pope lives) does not coincide with them, through they are located in the City of Rome. At the time that John wrote Revelation the Christians of Rome lived mostly in Trastevere (trans Tiber), a district "across the Tiber" from the City and adjacent to the Vatican hill, where St. Peter was crucified and buried. The Vatican is on top of that burial site and is today its own city-state distinct from Rome and Italy.
So, of what was St. John speaking when he wrote Revelation on the island of Patmos around 96 A.D.? Obviously of the pagan imperial system situated on the Seven Hills, especially the Capitoline (the religious and political center) and the Palatine (the imperial palace). This pagan power persecuted the Church of Rome in Nero's day (64-67 AD), and in the mid-nineties under the emperor Domitian was persecuting Christians throughout the Roman world. The people considered Domitian a re-incarnation of the evil Nero (the head that lives again). While the antichrist Nero persecuted only the Christians of Rome, Domitian extended that persecution throughout the empire. Both are thus types of the final persecutor, the Antichrist.
Why the cryptic name Babylon? First, the historical Babylon was the pagan power which persecuted the People of God, the Jews, between 610 and 538 BC, destroying the Temple and dispersing the people. The Romans inherited that mantle of infamy when they destroyed the Temple in 70 A.D., and, more importantly, persecuted the new People of God, the Church. Thus, St. Peter, writing from Rome refers to as "Babylon" (1 Pt. 5:13) - a name any Jew or Christian familiar with the Old Testament would know.
The person of the Antichrist
How does this relate to the Antichrist? The future Antichrist's government will be a world-wide power which will persecute the Catholic Church (and orthodox Christians, in general) everywhere. He will follow in the footsteps of the archetype of persecutors of God's People, the Babylonians, and the Romans who imitated them by persecuting the early Church. The “Babylon” of John's day, Rome, stands for the kingdom of the future Antichrist, but is no more likely to be situated in Italy than Rome needed to be situated in Babylon to fulfill this archetype. John was informing his readers of this prophetic type by drawing their attention to the contemporary fulfillment they found in imperial Rome.
The Catholic Church and the Antichrist
Finally, some ignore the only texts which actually tell us the religious beliefs of the Antichrist and how his spirit will be known down through history, and thereby how he opposes the spirit of Christ. In St. John's letters (1 John 4, 2 John 1), the Apostle states that the spirit of the Antichrist denies the Incarnation (the Son of God becoming man), and thereby also the Holy Trinity (the Father, Son and the Spirit). Since Jesus came to witness to the Father, to reconcile us to the Father, and to send the Church through the outpouring of the Holy Spirit, the first step of opposition is to attack the doctrines of the Trinity and the Incarnation. Indeed, history has already seen this spirit in “teachers” such as Arius, who denied Christ's divinity, in the modalists, who taught God was not Three Persons, but operated in different modes (as Father, or as Son, or as Spirit) , as well as in later movements, and some modern ones, which deny the Trinity, or the truth of the Incarnation.
On the other hand, having the spirit of Christ, rather than of antichrist, the Catholic Church has preserved these Truths, her General Councils of bishops formulated them precisely, in order that errors that deny them would be more easily detected, and the truths themselves more readily understood. Her saints and popes have defended them to this day, often at the cost of martyrdom. While no recent Popes have been martyrs (over thirty early ones were), all popes continue to teach and preach the Trinity and Jesus Christ.
In our own time, Pope John Paul II wrote three great encyclicals (circular letters) on the Trinity, one for each Divine Person, and, likely preached Jesus Christ to more people than any other person in human history. Pope Benedict emphasized the centrality of Christ in his writings and addresses, especially his 3-volume “Jesus of Nazareth.” Similarly, Pope Francis preaches Jesus as the Word made flesh who opens our minds and hearts to God, and to others, our “path and destination,” to be known and loved, but especially to be imitated.
Encyclicals of Pope John Paul II