The man of lawlessness is described in the New Testament Epistle to the church at Thessalonica. The Apostle Paul gives us some detail as to who he is and what to look for. It is generally supposed that this person cannot show up in this church age for a number of reasons. The most popular reasons include:
It appears that we are at the threshold of the coming of this man. He must come prior to the rapture of the church. The date of his coming during the church age is unknown, but his tenure after the church is raptured is known.
2 Peter 2:18-19
(18) For when they speak great swelling words of emptiness, they allure through the lusts of the flesh, through lewdness, the ones who have actually escaped from those who live in error.
(19) While they promise them liberty, they themselves are slaves of corruption; for by whom a person is overcome, by him also he is brought into bondage.
The "they" in the above verses are in reference to his associates prior to his arrival. Change "they" to "he" and you have the same message that he will present only with more force.
Whether he arrives with great fanfare or simply introduced to begin his visible work later remains to be seen. The important thing is what does his arrival have to do with you?
His arrival does not initiate the coming of the Lord, therefore, it is not necessary to:
2 Thessalonians 2:1-17
(1) Now, brethren, concerning the coming of our Lord Jesus Christ and our gathering together to Him, we ask you,
(2) not to be soon shaken in mind or troubled, either by spirit or by word or by letter, as if from us, as though the day of Christ had come.
(3) Let no one deceive you by any means; for that Day will not come unless the falling away comes first, and the man of sin is revealed, the son of perdition,
(4) who opposes and exalts himself above all that is called God or that is worshiped, so that he sits as God in the temple of God, showing himself that he is God.
(5) Do you not remember that when I was still with you I told you these things?
(6) And now you know what is restraining, that he may be revealed in his own time.
(7) For the mystery of lawlessness is already at work; only He who now restrains will do so until He is taken out of the way.
(8) And then the lawless one will be revealed, whom the Lord will consume with the breath of His mouth and destroy with the brightness of His coming.
(9) The coming of the lawless one is according to the working of Satan, with all power, signs, and lying wonders, (10) and with all unrighteous deception among those who perish, because they did not receive the love of the truth, that they might be saved.
(11) And for this reason God will send them strong delusion, that they should believe the lie,
(12) that they all may be condemned who did not believe the truth but had pleasure in unrighteousness.
(13) But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth,
(14) to which He called you by our gospel, for the obtaining of the glory of our Lord Jesus Christ.
(15) Therefore, brethren, stand fast and hold the traditions which you were taught, whether by word or our epistle.
(16) Now may our Lord Jesus Christ Himself, and our God and Father, who has loved us and given us everlasting consolation and good hope by grace,
(17) comfort your hearts and establish you in every good word and work.