and certain texts pulled from Daniel, Ezekiel, and Isaiah in the OT.
As I understand it there is actually very little specific mention of "Antichrist" or "antichrists" in the bible; most of the picture is developed from types, anti-types, symbols. etc., and varies according to historical time-period and theological persuasion.
The specific association with an individual Pope, or the Catholic Church in general, probably finds its root in the statement of the ante-Nicene Church bishop Polycarp (ca. 69 – ca. 155) who "warned the Philippians that everyone that preached false doctrine was an antichrist."
http://en.wikipedia.org/wiki/Antichrist#Post-Nicene_ChristianityYou can see how this would become useful for anyone disagreeing with the Church, even from within the Church itself; for example, the development of the idea of "Angelic Pope/Papal Antichrist" was a theme developed by various Catholic exegetes in association with the Monastic and Gregorian Reform movements, and the rise of the Papal Monarchy.
Protestantism incorporated the association with either the Pope or the Church (or both) early on.
The late 10th-century monk, Adso of Montier-en-Der, is (I think) the earliest surviving source for the full-blown description of Antichrist which contained the elements that would carry on through the Medieval period. His
Libellus de Antichristo ("Life of Antichrist" also known as "Life and Times of Antichrist" or simply "The Antichrist") was collated from the various ideas floating around in his day. Many of these elements continue today in the eschatology of Dispensationalists ("Left Behind" series, or Hal Lindsay's "Late Great Planet Earth" for instance).
Historicist interpretation, which was dominant in Protestantism during the 17th-thru-19th centuries, uses less of these elements and also (I think) places more specific emphasis on the Catholic Church as "Babylon" or the "Beast" power, and the Pope as Antichrist.
If you're interested in doing some reading on the historical development of the idea of the Antichrist, here is a list of books I have which I found interesting:
A couple of interesting ones on the history of Antichrist interpretation in America (covering both Dispensationalist and Historicist interpretations:Naming the Antichrist: The History of an American Obsession by Fuller
When Time Shall Be No More: Prophecy Belief in Modern American Culture by Paul Boyer
This one is especially good on explaining the Historicist interpretation of Seventh Day Adventism, one of the Protestant denominations which has retained the Papacy/Antichrist/Beast interpretation. Especially interesting because they assign a negative apocalyptic role to the United States, based on an expected destruction of Church/State separation and the loss of other Constitutionally protected rights:Adventism & the American Republic: Public Involvement Of A Major Apocalyptic Movement by Douglas Morgan
Another study on the development of Historicism:Antichrist in Seventeenth Century England by Christopher Hill
Historical development of the Antichrist theme itself:Antichrist by Bernard McGinn
Visions of the End by Bernard McGinn
The Apocalypse in the Middle Ages by Bernard McGinn
The Encyclopedia of Apocalypticism 3 volumes, various editors and authors. Very interesting survey from the origins of Jewish and Christian apocalyptic ideas through current interpretations.
The Antichrist Legend: A Chapter in Christian and Jewish Folklore by Bousset
Dominion of God: Christendom and Apocalypse in the Middle Ages by Whalen
Joachim of Fiore and the Prophetic Future by Reeves
Constructing Antichrist: Paul, Biblical Commentary, and the Development of Doctrine in the Early Middle Ages by Hughes