Grosey's Messages

 1 Now concerning the coming of our Lord Jesus Christ and our being gathered together to him, we ask you, brothers,1  2 not to be quickly shaken in mind or alarmed, either by a spirit or a spoken word, or a letter seeming 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 lawlessness2  is revealed, the son of destruction,3  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. 5 Do you not remember that when I was still with you I told you these things? 6 And you know what is restraining him now so that he may be revealed in his time. 7 For the mystery of lawlessness is already at work. Only he who now restrains it will do so until he is out of the way. 8 And then the lawless one will be revealed, whom the Lord Jesus will kill with the breath of his mouth and bring to nothing by the appearance of his coming. 9 The coming of the lawless one is by the activity of Satan with all power and false signs and wonders, 10 and with all wicked deception for those who are perishing, because they refused to love the truth and so be saved. 11 Therefore God sends them a strong delusion, so that they may believe what is false, 12 in order that all may be condemned who did not believe the truth but had pleasure in unrighteousness. 13 But we ought always to give thanks to God for you, brothers beloved by the Lord, because God chose you as the firstfruits4  to be saved, through sanctification by the Spirit and belief in the truth. 14 To this he called you through our gospel, so that you may obtain the glory of our Lord Jesus Christ. 15 So then, brothers, stand firm and hold to the traditions that you were taught by us, either by our spoken word or by our letter.
 16 Now may our Lord Jesus Christ himself, and God our Father, who loved us and gave us eternal comfort and good hope through grace, 17 comfort your hearts and establish them in every good work and word.

Ἐρωτῶμεν δὲ ὑμᾶς, ἀδελφοί, ὑπὲρ τῆς παρουσίας τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ καὶ ἡμῶν ἐπισυναγωγῆς ἐπ' αὐτόν, 2 εἰς τὸ μὴ ταχέως σαλευθῆναι ὑμᾶς ἀπὸ τοῦ νοὸς ⸀μηδὲ θροεῖσθαι μήτε διὰ πνεύματος μήτε διὰ λόγου μήτε δι' ἐπιστολῆς ὡς δι' ἡμῶν, ὡς ὅτι ἐνέστηκεν ἡ ἡμέρα τοῦ ⸀κυρίου. 3 μή τις ὑμᾶς ἐξαπατήσῃ κατὰ μηδένα τρόπον· ὅτι ἐὰν μὴ ἔλθῃ ἡ ἀποστασία πρῶτον καὶ ἀποκαλυφθῇ ὁ ἄνθρωπος τῆς ⸀ἀνομίας, ὁ υἱὸς τῆς ἀπωλείας, 4 ὁ ἀντικείμενος καὶ ὑπεραιρόμενος ἐπὶ πάντα λεγόμενον θεὸν ἢ σέβασμα, ὥστε αὐτὸν εἰς τὸν ναὸν τοῦ ⸀θεοῦ καθίσαι ἀποδεικνύντα ἑαυτὸν ὅτι ἔστιν θεός. 5 οὐ μνημονεύετε ὅτι ἔτι ὢν πρὸς ὑμᾶς ταῦτα ἔλεγον ὑμῖν; 6 καὶ νῦν τὸ κατέχον οἴδατε, εἰς τὸ ἀποκαλυφθῆναι αὐτὸν ἐν τῷ ⸀ἑαυτοῦ καιρῷ· 7 τὸ γὰρ μυστήριον ἤδη ἐνεργεῖται τῆς ἀνομίας· μόνον ὁ κατέχων ἄρτι ἕως ἐκ μέσου γένηται. 8 καὶ τότε ἀποκαλυφθήσεται ὁ ἄνομος, ὃν ὁ κύριος ⸀Ἰησοῦς ⸀ἀνελεῖ τῷ πνεύματι τοῦ στόματος αὐτοῦ καὶ καταργήσει τῇ ἐπιφανείᾳ τῆς παρουσίας αὐτοῦ, 9 οὗ ἐστιν ἡ παρουσία κατ' ἐνέργειαν τοῦ Σατανᾶ ἐν πάσῃ δυνάμει καὶ σημείοις καὶ τέρασιν ψεύδους 10 καὶ ἐν πάσῃ ἀπάτῃ ⸀ἀδικίας τοῖς ἀπολλυμένοις, ἀνθ' ὧν τὴν ἀγάπην τῆς ἀληθείας οὐκ ἐδέξαντο εἰς τὸ σωθῆναι αὐτούς· 11 καὶ διὰ τοῦτο ⸀πέμπει αὐτοῖς ὁ θεὸς ἐνέργειαν πλάνης εἰς τὸ πιστεῦσαι αὐτοὺς τῷ ψεύδει, 12 ἵνα κριθῶσιν ⸀πάντες οἱ μὴ πιστεύσαντες τῇ ἀληθείᾳ ἀλλὰ εὐδοκήσαντες ⸀τῇ ἀδικίᾳ.
 13 Ἡμεῖς δὲ ὀφείλομεν εὐχαριστεῖν τῷ θεῷ πάντοτε περὶ ὑμῶν, ἀδελφοὶ ἠγαπημένοι ὑπὸ κυρίου, ὅτι εἵλατο ὑμᾶς ὁ θεὸς ⸀ἀπαρχὴν εἰς σωτηρίαν ἐν ἁγιασμῷ πνεύματος καὶ πίστει ἀληθείας, 14 εἰς ⸀ὃ ἐκάλεσεν ὑμᾶς διὰ τοῦ εὐαγγελίου ἡμῶν, εἰς περιποίησιν δόξης τοῦ κυρίου ἡμῶν Ἰησοῦ Χριστοῦ. 15 ἄρα οὖν, ἀδελφοί, στήκετε, καὶ κρατεῖτε τὰς παραδόσεις ἃς ἐδιδάχθητε εἴτε διὰ λόγου εἴτε δι' ἐπιστολῆς ἡμῶν.
 16 Αὐτὸς δὲ ὁ κύριος ἡμῶν Ἰησοῦς Χριστὸς καὶ ⸀θεὸς ⸀ὁ πατὴρ ἡμῶν, ὁ ἀγαπήσας ἡμᾶς καὶ δοὺς παράκλησιν αἰωνίαν καὶ ἐλπίδα ἀγαθὴν ἐν χάριτι, 17 παρακαλέσαι ὑμῶν τὰς καρδίας καὶ ⸀στηρίξαι ἐν παντὶ ⸂ἔργῳ καὶ λόγῳ⸃ ἀγαθῷ.

A word meaning is often determined by its context.

There has been debate about the meaning of apostasia in verse 3.  ὅτι ἐὰν μὴ ἔλθῃ ἡ ἀποστασία πρῶτον καὶ ἀποκαλυφθῇ ὁ ἄνθρωπος τῆς ⸀ἀνομίας, ὁ υἱὸς τῆς ἀπωλείας,

The root of the word is apo .. from... stasia  stand .. or stand away from.

Apostasia sounds like our English word "Apostasy".

Some see it as indicating the rapture.. when believers are seized away.

This is a possible meaning, as there are similar uses of the word elsewhere in the New Testament.

Stand away from....

Elsewhere in this passage a similar word derived from the same basic root is used.

15 ἄρα οὖν, ἀδελφοί, στήκετε, καὶ κρατεῖτε τὰς παραδόσεις ἃς ἐδιδάχθητε εἴτε διὰ λόγου εἴτε δι' ἐπιστολῆς ἡμῶν.

16 Αὐτὸς δὲ ὁ κύριος ἡμῶν Ἰησοῦς Χριστὸς καὶ ⸀θεὸς ⸀ὁ πατὴρ ἡμῶν, ὁ ἀγαπήσας ἡμᾶς καὶ δοὺς παράκλησιν αἰωνίαν καὶ ἐλπίδα ἀγαθὴν ἐν χάριτι, 17 παρακαλέσαι ὑμῶν τὰς καρδίας καὶ ⸀στηρίξαι ἐν παντὶ ⸂ἔργῳ καὶ λόγῳ⸃ ἀγαθῷ.

Similar concepts of stengthening flow over into chapter 3 πιστὸς δέ ἐστιν ὁ κύριος, ὃς στηρίξει ὑμᾶς καὶ φυλάξει ἀπὸ τοῦ πονηροῦ. 4 πεποίθαμεν δὲ ἐν κυρίῳ ἐφ' ὑμᾶς, ὅτι ἃ ⸀παραγγέλλομεν καὶ ποιεῖτε καὶ ποιήσετε. 5 ὁ δὲ κύριος κατευθύναι ὑμῶν τὰς καρδίας εἰς τὴν ἀγάπην τοῦ θεοῦ καὶ εἰς τὴν ὑπομονὴν τοῦ Χριστοῦ.

it appears that Paul's central idea is the believers are chosen, and their election is proven by their continuing to stand in the truth of the gospel and in the love of God. satan opposes these two things. In fact, during the last time the one who establishes beliebvers in the truth and restrains Satan will be taken away.  Then the antichrist will be revealed, and those in the world will be deceived and follow on in his lies, deceived through his miracles, and through God's judgement on them allowing them to be decieved.

καὶ νῦν τὸ κατέχον οἴδατε, εἰς τὸ ἀποκαλυφθῆναι αὐτὸν ἐν τῷ ⸀ἑαυτοῦ καιρῷ·

At a particular point in time, before the return of the Lord Jesus Christ, before satan is revealed, sitting himself in the temple of God proclaiming himself to be God,  the Restrainer (I would say from the repeated reference to the Holy Spirit throughout this passage that the Person referred to is the Holy Spirit) will be taken away (apostasia verese 3), and then everything else will proceeed from bad to worse as satan gains power, until the return of the Lord Jesus in glory to destroy him and those who followed him in oppressing Christians ( 2 Thess 1:8-10).

Hence:

One day the Holy Spirit's influence on the world will be removed.

People will joyfully and willingly follow Satan.

The Lord Jesus will return and dedstroy Satan and his works.

Given that reference is made in 2:1-3 of  1 Thessalonians , and rapture of the believers in 1 Thess 4 and 5, I would assume that the removal of the Holy Spirit from the world is at the same time that believers are removed from the world at the rapture, when the Lored Jesus returns for His Church, true believers.

Then the Antichrist will be revealed and reign on earth for a period of time (maybe 7 years of the book of Revelation).

Then the Lord Jesus Christ will return to destroy satan and His works.