2 As to the coming of our Lord Jesus Christ and our being gathered together to him, we beg you, brothers and sisters,[a] 2 not to be quickly shaken in mind or alarmed, either by spirit or by word or by letter, as though from us, to the effect that the day of the Lord is already here. 3 Let no one deceive you in any way; for that day will not come unless the rebellion comes first and the lawless one[b] is revealed, the one destined for destruction.[c] 4 He opposes and exalts himself above every so-called god or object of worship, so that he takes his seat in the temple of God, declaring himself to be God. 5 Do you not remember that I told you these things when I was still with you? 6 And you know what is now restraining him, so that he may be revealed when his time comes. 7 For the mystery of lawlessness is already at work, but only until the one who now restrains it is removed. 8 And then the lawless one will be revealed, whom the Lord Jesus[d] will destroy[e] with the breath of his mouth, annihilating him by the manifestation of his coming.
2 Thessalonians 2:1-8
the falling away is here as you have well documented. the two witnesses of Revelation are dead ( the Church ) and the world is rejoicing. the remnant has headed to the mountains ( prayer, looking up to clouds waiting for the imminent return of our Lord Jesus Christ )
That’s one way to explain it, and indeed a relative remnant is what is saved, but we disagree where the majority of that resides.