The Protestant churches today and even some brethren are backing away from identifying the Antichrist power, and yet the Reformers and even those before them saw clearly who the Antichrist was. What is happening to the churches today, are they becoming blind and forgetful of the truth they once saw clearly, as to who was the leader of the Antichrist entity, and gave scriptural proof.
Here is good description of Martin Luther's conviction on this...
"Luther came to think of the pope as the Antichrist because, first, of what the general tradition was about where to find the Antichrist. The Antichrist was someone subverting the Church from within. That was the expectation popularly. And when he saw the papal office and read the histories and saw it subverting the gospel as he understood it, he became convinced that that was the proof that the papal office was the office of the Antichrist, trying to destroy God's church from within.
The pope claimed to be Christ's representative on earth. Luther became convinced that the pope was the devil's representative on earth. And that took graphic form very early in the Reformation ... with one of the most effective pieces of propaganda in the early Reformation: a series of 26 woodcuts that juxtaposed some action in Christ's life with something in the papacy. Christ carrying his cross to be crucified; the pope being carried in his throne on the backs of people ... . Christ washing the feet of the disciples; the pope having his feet kissed. And over and over again, scenes from Christ's life juxtaposed with scenes from the papacy. ... Christ was always humble and serving; the papacy, the pope was always lordly and [lording] over others. Christ is Christ; the pope is Antichrist.
At the end of his life, Martin Luther decided he had to issue his final testament against all the enemies of the gospel. And he published treatises, he encouraged people, but words were not sufficient. He also had to use images. And so he asked his friend, the painter Lucas Cranach, to do a series of woodcuts, and Luther wrote the verses for them. And these woodcuts were designed to show as graphically as possible, to those who could read and those who couldn't, what Luther thought of the papacy. So for example, there's a woodcut which shows the pope on his throne and peasants with their tongues out, their trousers down, farting in the pope's face. Another one shows the pope riding an ass, holding a pile of dung in his hands, saying "The pope is offering a counsel." And another that shows the German emperor lying on the ground with the pope with his foot on the emperor's neck, which shows, once again graphically, Luther's belief that the papacy was trying to control secular authority throughout the world. These were all actions of the Antichrist, and Luther wanted to make it clear what he thought of the pope".... Apocalypticism Explained | Apocalypse! FRONTLINE | PBS
The title of the Pope, 'Pontifex Maximus', can be traced all the way back to ancient Babylon and its system of pagan worship. The Babylon kings served as both king and priest of the pagan Babylonian Mystery religion. As priests, they bore the title "Pontifex Maximus" or "Supreme Pontiff," meaning "supreme pathfinder" or "bridge maker," representing "the path or connection between this life and the next", or they held the keys to the next life. When Medo-Persia conquered Babylon, the Babylonian pagan religion was maintained, but there was a revolt of the priesthood so consequently the priests of Babylon were driven out of Medo-Persia, and established themselves at Pergamum, does the name sound familiar. Well they took with them their titles and vestures and set about to continued their reign there as priest-kings of Babylonian paganism and we find the scripture refers to it:
Revelation 2:12-14 King James Version (KJV)
12 And to the angel of the church in Pergamos write; These things saith he which hath the sharp sword with two edges;
13 I know thy works, and where thou dwellest, even where Satan's seat is: and thou holdest fast my name, and hast not denied my faith, even in those days wherein Antipas was my faithful martyr, who was slain among you, where Satan dwelleth.
14 But I have a few things against thee, because thou hast there them that hold the doctrine of Balaam, who taught Balac to cast a stumblingblock before the children of Israel, to eat things sacrificed unto idols, and to commit fornication.
The pontiff king of Pergamum Attalus III lived from 170 BC – 133 BC, and in his will he left the kingdom to the emperor of Rome in 133 BC and the kingdom of Pergamum merged with the Roman Empire along with what the Bible calls Satan throne and idol worship and its title "Pontifex Maximus".
The pagan title was taken over by the bishop of Rome, as we see it in In Emperor Theodosius's edict De fide catholica of 380 AD. By this time, the Roman bishops had amassed much political as well as religious power, and so the bishop of Rome was elected 'Pontifex Maximus', becoming the official pagan Babylonian priest seated on Satan's throne in Rome. As such, the bishop introduced the worship of pagan Babylon with its rites and rituals and pagan sacraments, "converted" the pagan temples of Rome into "Christian churches" but at the same time allowed pagan worship to come in.
The Roman bishop Damasus exercised his authority as head of 'Babylonian paganism in Rome', and replaced all the Christian elders with pagan priests and continued the practice of basically the Babylonian Mystery religion and we can see how it spread in Roman Empire from there, and was pointed out by the Reformation and its leaders and nothing has changed.