Paul was speaking in 2 Th 2:1 (Geneva Bible): Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our assembling unto him,
2 Th 2:2 (NLT): Don’t be so easily shaken or alarmed by those who say that the day of the Lord has already begun. Don’t believe them, even if they claim to have had a spiritual vision, a revelation, or a letter supposedly from us.
2 Th 2:3 (Geneva Bible): Let no man deceive you by any means: for that day shall not come, except there come a departing first, and that that man of sin be disclosed, even the son of perdition.
"That day" in verse 3 refers back to "the day of the Lord" in verse 2. Therefore, it is unmistakable that these three verses are about the pre-Trib timing of the rapture.
Liddell & Scott Greek-English Lexicon gives two definitions for "apostasia" [which is in the Greek verse 3]: (1) defection; revolt; and (2) departure; disappearance. Departure, in Greek, is related to disappearance. Which definition fits verse 3, when we know for sure the context is the rapture?
2 Thes. 2:1. NOW CONCERNING the coming of our Lord Jesus Christ and our assembling to meet him, we beg you, brethren,
2. not to be quickly shaken in mind or excited, either by spirit or by word, or by letter purporting to be from us, to the effect that the day of the Lord has come.
3. Let no one deceive you in any way; for that day will not come, unless the rebellion comes first, and the man of lawlessness is revealed, the son of perdition,
4. who opposes and exalts himself against every so-called god or object of worship, so that he takes his seat in the temple of God, proclaiming himself to be God. (RSV)
Liddell & Scott's Greek-English Lexicon is NOT a lexicon of the New Testament—or even of Koine Greek! It is a lexicon of classical Greek literature—a very different dialect that is never used in the New Testament. Moreover, the meaning “departure; disappearance” is NEVER used in the New Testament! The only meanings found in the New Testament are, “defiance of established system or authority,” that is “rebellion, abandonment, breach of faith” (BDAG, p. 121). Furthermore, Liddell & Scott's Greek-English Lexicon was originally published in 1843 and the most recent edition was published in 1940.
The current Greek-English lexicon of the New Testament is A Greek-English Lexicon of the New Testament and other early Christian Literature, Third Edition (BDAG) published in 2000 by The University of Chicago Press. The pedigree of this lexicon would be in order here,
By the early 1900’s, the new studies in the lexicography of Koine Greek had become so great in number and significance that Erwin Preuschen published his Greek-German lexicon in 1910. Upon his death in 1920, the revision of his lexicon was entrusted to Walter Bauer and this revision was published in 1928 as the second edition. In 1930, James Hope Mouton and George Milligan independently published
The Vocabulary of the Greek Testament. A thoroughly revised edition of the Preuschen lexicon was published in 1937 with only Bauer’s name on the title page. Bauer realized, however, that his lexicon, although a huge improvement over Thayer’s in terms of accuracy and completeness, needed to be thoroughly revised and updated and therefore undertook a thorough search of all Greek literature down to the Byzantine times to determine more precisely the meaning of the words found in the New Testament. This resulted in the publication of the monumental work,
Griechisch-Deutsches Wörterbuch zu den Schriften des Neuen Testaments und der übrigen urchristlichen Literatur in 1949-1952. An English translation (by William F. Arndt and F. Wilbur Gingrich) of this lexicon was published by the University of Chicago in 1957 with the title,
A Greek-English Lexicon of the New Testament and other Early Christian Literature and became widely known as the “Bauer, Arndt, and Gingrich Lexicon.” A second edition was published by the University of Chicago in 1979. A thorough revision by Frederick William Danker was published by the University of Chicago in 2000. It is very commonly referred to simply as the “BDAG” and this name appears on the title page in parenthesis below the full title.
This outstanding lexicon is used today in Bible colleges, seminaries, and universities around the world and has been cited hundreds of thousands of times simply as, “BDAG”.
Now back to the New Testament passage under consideration,
2 Thes. 2:1. NOW CONCERNING the coming of our Lord Jesus Christ and our assembling to meet him, we beg you, brethren,
2. not to be quickly shaken in mind or excited, either by spirit or by word, or by letter purporting to be from us, to the effect that the day of the Lord has come.
3. Let no one deceive you in any way; for that day will not come, unless the rebellion comes first, and the man of lawlessness is revealed, the son of perdition,
4. who opposes and exalts himself against every so-called god or object of worship, so that he takes his seat in the temple of God, proclaiming himself to be God. (RSV)
What we have here is Christians in Thessalonica who are afraid that they have missed the rapture and Paul assuring them that that is not possible because the rapture will be
preceded by the foretold rebellion and the revealing of the man of lawlessness.