John Wycliffe
"When the western church was divided for about 40 years between two rival popes, one in Rome and the other in Avigon, France, each pope called the other pope antichrist - and John Wycliffe is reputed to have regarded them as both being right: "two halves of Antichrist, making up the perfect Man of Sin between them." -Ibid

Martin Luther (Lutheran)
"We here are of the conviction that the papacy is the seat of the true and real Antichrist...personally I declare that I owe the Pope no other obedience than that to Antichrist." (Aug. 18, 1520) Taken from The Prophetic Faith of Our Fathers, Vol. 2., pg. 121 by Froom. (In response to a papal bull [official decree]): "I despise and attack it, as impious, false... It is Christ Himself who is condemned therein... I rejoice in having to bear such ills for the best of causes. Already I feel greater liberty in my heart; for at last I know that the pope is antichrist, and that his throne is that of Satan himself." --D'Aubigné, b.6, ch. 9

Cotton Mather (Congregational Theologian)
"The oracles of God foretold the rising of an Antichrist in the Christian Church: and in the Pope of Rome, all the characteristics of that Antichrist are so marvelously answered that if any who read the Scriptures do not see it, there is a marvelous blindness upon them." Taken from The Fall of Babylon by Cotton Mather in Froom's book, The Prophetic Faith of Our Fathers, Vol. 3, pg. 113.

John Wesley (Methodist)
Speaking of the Papacy he said, "He is in an emphatical sense, the Man of Sin, as he increases all manner of sin above measure. And he is, too, properly styled the Son of Perdition, as he has caused the death of numberless multitudes, both of his opposers and followers... He it is...that exalteth himself above all that is called God, or that is worshipped...claiming the highest power, and highest honour...claiming the prerogatives which belong to God alone." Taken from Antichrist and His Ten Kingdoms by John Wesley, pg. 110.
 

Ellen G. White: Seven Day Adventists
"This compromise between paganism and Christianity resulted in the development of "the man of sin" foretold in prophecy as opposing and exalting himself above God. That gigantic system of false religion is a masterpiece of Satan's power--a monument of his efforts to seat himself upon the throne to rule the earth according to his will.

Thomas Cranmer (Anglican)
"Whereof it followeth Rome to be the seat of antichrist, and the pope to be very antichrist himself. I could prove the same by many other scriptures, old writers, and strong reasons." (Referring to prophecies in Revelation and Daniel.) Taken from Works by Cranmer, Vol. 1, pp. 6-7.

Roger Williams (First Baptist Pastor in America)
He spoke of the Pope as "the pretended Vicar of Christ on earth, who sits as God over the Temple of God, exalting himself not only above all that is called God, but over the souls and consciences of all his vassals, yea over the Spirit of Christ, over the Holy Spirit, yea, and God himself...speaking against the God of heaven, thinking to change times and laws; but he is the son of perdition (II Thess. 2)." Taken from The Prophetic Faith of Our Fathers by Froom, Vol. 3, pg. 52.

John Knox (Scotch Presbyterian)
Knox wrote to abolish "that tyranny which the pope himself has for so many ages exercised over the church" and that the pope should be recognized as "the very antichrist, and son of perdition, of whom Paul speaks." Taken from The Zurich Letters, pg. 199 by John Knox.

John Calvin (Presbyterian)
"Some persons think us too severe and censorious when we call the Roman pontiff Antichrist. But those who are of this opinion do not consider that they bring the same charge of presumption against Paul himself, after whom we speak and whose language we adopt... I shall briefly show that (Paul's words in II Thess. 2) are not capable of any other interpretation than that which applies them to the Papacy." Taken from Institutes by John Calvin.

2 Thessalonians 2:1-12 (KJV)

1  Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him,
2  That ye be not soon shaken in mind, or be troubled, neither by spirit, nor by word, nor by letter as from us, as that the day of Christ is at hand.
3  Let no man deceive you by any means: for that day shall not come, except there come a falling away first, and that man of sin be revealed, the son of perdition;
4  Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
5  Remember ye not, that, when I was yet with you, I told you these things?
6  And now ye know what withholdeth that he might be revealed in his time.
7  For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way.
8  And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming:
9  Even him, whose coming is after the working of Satan with all power and signs and lying wonders,
10  And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved.
11  And for this cause God shall send them strong delusion, that they should believe a lie:
12  That they all might be damned who believed not the truth, but had pleasure in unrighteousness.