For the readers who've not yet seen the article (related to the Subject under present discussion), posted in the past:
[quoting]
"[Kenneth S. Wuest is a member of the Faculty of the Moody Bible Institute, Chicago, Illinois, and author of numerous books on New Testament Greek.]"
"The Rapture: Precisely When?" - Kenneth S Wuest
"The answer to these questions will only be convincing to the reader if it is based upon the rules of Biblical exegesis. [...<snip>...] That interpretation which is based upon the above rules is to be regarded as correct until it can be shown by the reapplication of the same rules that an error of human judgment has crept in.
"There is such a thing, therefore, as a scientific method of studying the Word. The student who follows the rules of an experiment in chemistry brings that experiment to a successful conclusion. The student who does not ends up with an explosion. Just so, the student who conducts his study of the Bible along the scientific lines noted above arrives at the correct interpretation, and the student who does not at the wrong one. The exegetical method the student uses in answering the question with reference to the time of the rapture will determine whether he believes in a pretribulational or a posttribulational rapture.
[...]
"The words "a falling away" are the Authorized Version rendering of apostasia. The verbal form afistamai from which it comes is present middle of afisthmi, the root verb, which we will study. The simple verb Jisthmi [histemi] in its intransitive sense means "to stand," the prefixed preposition means "off, away from," and the compound verb, "to stand off from." The word does not mean "to fall." The Greeks had a word for that, piptw. Afisthmi, in its various uses, is reported by Thayer as follows: "to make stand off, cause to withdraw, to stand off, stand aloof, to desert, to withdraw from one"; in contexts where a defection from the faith is in view, it means "to fall away, become faithless." The verb is rendered by the translators of the Authorized Version "to depart," in Luke 2:32; Luke 4:13; Luke 13:27; Acts 12:10; Acts 15:38; Acts 19:9; Acts 22:29; 2 Corinthians 12:8; 1 Timothy 4:1; 2 Timothy 2:19; Hebrews 3:12. In Luke 8:13 it is translated "fall away," in Acts 5:37, "drew away," and in Acts 5:38, "refrain." Had they translated the word here instead of interpreting it, they would have rendered it by the word "departure." The reader will observe that the predominant translation of the verbal form is "to depart," also, that where it is translated "fall away," the context adds the idea of "falling away" to the verb, which action is still a departure.
E. Schuyler English, to whom this present writer is deeply indebted for calling his attention to the word "departure" as the correct rendering of apostasia in this context, also informs us that the following translators understood the Greek word to mean "a departure" in this context: Tyndale (1534), Coverdale (1535), the Geneva Bible (1537), Cranmer (1539), and Beza (1565), and so used it in their translations. Apostasia is used once more in the New Testament and is translated "to forsake" (AV), signifying a departure. The neuter noun apostasion in Matthew 5:31; Matthew 19:7; and Mark 10:4 is rendered by the Authorized Version, "divorcement," which word also signifies a departure, here, from antecedent relations.
The writer is well aware of the fact that apostasia was used at times both in classical and koine Greek in the sense of a defection, a revolt in a religious sense, a rebellion against God, and of the act of apostasy. Liddell and Scott in their classical lexicon give the above as the first definition of the word. Moulton and Milligan quote a papyrus fragment where the word means "a rebel." But these are acquired meanings of the word gotten from the context in which it is used, not the original, basic, literal meaning, and should not be imposed upon the word when the context does not qualify the word by these meanings, as in the case of our Thessalonians passage, where the context in which apostasia is embedded does not refer to a defection from the truth but to the rapture of the church. The fact that our word "apostasy" means a defection from the truth is entirely beside the point since we do not interpret Scripture upon the basis of a transliterated word to which a certain meaning has been given, but upon the basis of what the Greek word mean to the first century reader. The fact that Paul in 1 Timothy 4:1 uses this verb in the words "some shall depart from the faith" and finds it necessary to qualify its meaning by the phrase "from the faith" indicates that the word itself has no such connotation. The translators of the Authorized Version did not translate the word, but offered their interpretation of it. They should have translated it and allowed the student to interpret it in its context.
With the translation of the word before us, the next step is to ascertain from the context that to which this departure refers. We note the presence of the Greek definite article before apostasia, of which the translation takes no notice. A Greek word is definite in itself, and when the article is used the exegete must pay particular attention to it. "The basal function of the article is to point out individual identity. It does more than mark 'the object as definitely conceived,' for a substantive in Greek is definite without the article." This departure, whatever it is, is a particular one, one differentiated from all others. Another function of the article is "to denote previous reference." Here the article points out an object the identity of which is defined by some previous reference made to it in the context." Paul in 2 Thessalonians 2:1 has just spoken of the coming of the Lord. This coming is defined by the words "our gathering together unto him," not as the second advent, but as the rapture. The Greek word rendered "and" can also be translated "even," and the translation reads, "the coming of our Lord Jesus Christ, even our gathering together unto him."
The article before apostasia defines that word by pointing to "the gathering together unto him" as that departure. This article determines the context which defines apostasia. The translators took the context of 2 Thessalonians 2:10-12 as deciding the significance of the word, but they went too far afield, not grasping the function of the definite article preceding apostasia which points back to the rapture of 2 Thessalonians 2:1, not ahead to the refusal to believe the truth of 2 Thessalonians 2:10-12. The article is all-important here, as in many instances of its use in the Greek New Testament. In 1 Thessalonians 4:13-18, Paul had given these saints teaching on the rapture, and the Greek article here points to that which was well known to both the reader and the writer, which is another use of the Greek definite article. Thus, the departure of the church from earth to heaven must precede the great tribulation period [I would say, "must precede the [7-yr] tribulation period" to be more specific (for 'GREAT tribulation' refers only to the latter half of it)]. And we have answered our questions again. It might be added that the reason why Paul merely speaks of a pretribulation rather than a preseventieth week rapture is that he is addressing himself to the needs of the Thessalonian saints and is not explaining the particular place of the rapture in the prophetic program of God."
--Kenneth S Wuest, "The Rapture--Precisely When?", Bibliotheca Sacra, BSac 114:453 (Jan 57), p.60
[ www. galaxie . com/article/bsac114-453-05 ]
[end quoting that post; bold and underline mine]