If you dig into the Greek of this passage you’ll see those who practice lawlessness are ones who never professed faith in Christ…and only Christ.
Sorry, Dude, they are PROFESSING Christ. Absolutely clear in those texts. Their downfall is LAWLESSNESS, as will be what gets most of Christianity. Most will not be saved.
That includes billions of professing Christians at the end of the world (no secret PTR will save them, because it’s a lie). They will gladly receive the mark of the beast, because it’s about God’s law, which their false teachers and pastors have convinced doesn’t apply to them. Guaranteed.