John said, "they went out from us..." I John 2:19 and that there were many in his day who went out from the church, drawing disciples after themselves, openly denying that Jesus was the Christ. Paul also said that shortly after his departure, grievous wolves would come in among them. But these false teachers were mere dwarves compared to the giant who would stand up among them centuries later. The Antichrist couldn't fully rise to power until the fall of the civil Roman empire. In I Thessalonians 2 Paul speaks of this, that the the man of sin had to be revealed, who opposes God and exalts himself above God. But he says something was then holding this wicked spirit back from fully manifesting himself...he is reticent to say what and who it is, lest his letter fall into the hands of the authorities, and the church undergo even further persecution. Because he says, "ye know WHAT withholdeth..." so he reminds them of how he told them in person back in verse 5 and that they knew at that time what was holding back the rise of Antichrist, the Roman empire. Then in verse 7 he states this mystery of iniquity was already at work, but now Paul speaks of a HE who will not allow the rise of THE Antichrist at that time, that is, Caesar himself. Because Antichrist would sit on a throne of spiritual and civil power at the same time and this would be impossible with Caesar in power. So "he who now letteth, will let until he be taken out of the way." Paul could not openly speak of the removal of the Emperor from his throne without unnecessarily putting the church at greater risk.
So the Roman beast then centuries later is slain and the Roman empire falls. Now rises THE Antichrist from the grave and ascends out of the bottomless pit. He comes from within the visible church, the temple of God, and exalts himself to be the holy Father, the vicar of Christ, and that his decrees supersede and cancel the inspired scriptures. He claims to be the Lord God on earth (check official Catholic doctrine). Because Satan found that his most effective strategy against Christ and His true church, was to provide a counterfeit Christ and church. And so the Pope would claim to be in Christ's place, posing as a friend of God and yet denying him. The very nature of what the Pope has done to oppose Christ, by counterfeiting him, acting in place of Him, is the true fulfillment of denying that Jesus is the Christ. The Pope doesn't openly deny Christ or God, he has found that the most subtle and effective of all methods is to deny Him by supplanting Him. So he is called the son of perdition in I Thessalonians 2:4 which was the name given to Judas, the betrayer of Christ. Antichrist is no mere civil ruler way off in the future, he is a betrayer of Jesus Christ. This is the ultimate betrayal.
And so the whole world wonders after the beast and worships him. And the kings of the earth give their power to him and subject themselves to him. And so he sends out his armies and priests to conquer and to kill whoever will not bow to him and take his brand on their foreheads. True Christians are burned alive, tortured, mutilated...men, women and children. The Waldensies were burned alive in a cave, choked to death by the smoke, men and women were filled with gun powder and blown up. Millions of God's elect all over the earth, over many long, dark, bloody centuries were slain by the beast, for not taking the mark of the papal beast and bowing to his image, and for standing for the truth.
But this woman, drunken with the blood of the saints has her end, and strong is the Lord God who judges her. Her sins have reached up to heaven and she shall receive double at the Lord's hand. At the brightness of His coming shall this Wicked be destroyed.
It's all documented, written down and signed with the blood of our brethren who now reign with Christ in heaven. They loved not their lives unto death. And we would do well to recognize all these things. To sit here in our modern age, and say that these these things have only a future fulfillment in something that will be really bad is laughable. But I think it possible though that at the end of the day, the Antichrist over there on the 7 hills in Rome may indeed rise up one more time in his full strength and lead one more full attack on God's people, and that in the midst of that, Christ will come. See Rev. 20:8-9