In the Church, from the beginning, there are some who are written in the book, and others, who aren't. The "mystery of iniquity" (2 Thess 2) are the latter. They are members of the Church, i.e. they are "called", but they're not predestined, i.e. "chosen". In Mt 13, you got the wheat and the cockle growing in the field/Church.
One day, the Lord will take away the peg (tent-nail) and the tabernacle/tent/Church will collapse (Is 22:25). Neither Antichrist, nor the devil are able to bring down the Church.The gates of hell won't prevail. Rather the Lord will take away the mass (Dan), take away the pope (Is 22:25), and take away the shepherds, and let most Catholics fall into apostasy, such that Antichrist and the devil get their share, the birds get their great supper of God (Rev 19:17).
Q: Why does God do that?
A: "because thou hast not known the time of thy visitation" (Lk 19:44)
Jerusalem/the Church hasn't known the time of the first/second coming of Christ. Pope Leo XIII knew that St. Michael and his angels fought with the dragon (Rev 12), St. Pope Pius X said that things look like Antichrist was already born, and he was (whether Roncalli or Montini). But right after Pius X the Church stopped to care about the topic. Catholics were reeducated to stop being "prophets of doom" (Roncalli before the robber council).
Christ made blind men see, lame men walk, and dead men live. The announced signs. But Jerusalem didn't know the time of her visitation. The Gospel had been preached everywhere, most Catholics were liberal, but they didn't know the time of the Church's visitation. Even trads up to this day say: let's continue the Church, let's continue the mass, let's rebuild the Church, etc.
But our Lord already pulled the peg, pulled the plug, because thou hast not known the time of thy visitation.
The beast in Rev 13 is the sum of the beasts of Daniel. That's Fɾҽҽmαsσɳɾყ/liberalism/modernism/... transforming the "mystery of iniquity" part of the Church (not written in the book) into beast. All confessions and deeds (forehead/hand) in favour of this world mark you as part of the beast. You're part of the beast, if thou hast not known the time of the visitation of the Church.
If you think about Pfizer, Kushner, Schwab, Graphene, or any other type of Jooo, you missed the sound of the trumpet!
Those who don't believe, are already damned. The Apocalypse is about the bipartite Church, about the separation of the wheat from the chaff, "within" the Church.