We are not waiting for the restrainer to be removed. It already happened in 476 AD.
"And now ye know what withholdeth that he might be revealed in his time."
2 Thessalonians 2:6
"What withholdeth" -- the restraining power. Paul's audience already knew what it was.
"For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way."
2 Thessalonians 2:7
The mystery of lawlessness was already at work in Paul's day. The restrainer would be removed.
"And then shall that Wicked be revealed, whom Yahusha shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming."
2 Thessalonians 2:8
Once the restrainer is removed, the lawless one is revealed -- and operates until Yahusha returns.
Paul tells the Thessalonians, "ye know what withholdeth." He had already told them in person. But he could not write it in a letter. Why? Because identifying the Roman Empire as the power that must be "taken out of the way" would have been considered treason -- punishable by death.
Every early church writer understood this. The restrainer was Pagan Rome -- the Caesars. As long as the imperial Caesars ruled, the Papacy could not rise to full power. The two systems were incompatible: one was political-pagan, the other religious-apostate. The Papacy needed the political vacuum left by Rome's collapse.
"What obstacle is there but the Roman state, the falling away of which, by being scattered into ten kingdoms, shall introduce Antichrist?" -- Tertullian (c. 200 AD), On the Resurrection of the Flesh, Chapter 24
"He who now restrains will do so until he is out of the way, that is, when the Roman Empire is taken out of the midst, then the lawless one will be revealed." -- Chrysostom (c. 390 AD), Homily on 2 Thessalonians
Paul writes (c. 51 AD): The mystery of iniquity "doth already work." The seeds of apostasy were planted even in the apostolic era. But the restrainer -- imperial Pagan Rome -- held it back.
Rome falls (476 AD): The last Western Roman Emperor, Romulus Augustulus, is deposed. The restrainer is "taken out of the way." The political vacuum is created.
The Papacy rises (538 AD): Emperor Justinian's decree gives the Bishop of Rome supreme ecclesiastical authority. The last of the three opposing Arian kingdoms (the Ostrogoths) is uprooted. The lawless one is fully revealed with civil and religious authority.
1,260 years of dominion (538-1798 AD): Exactly as Daniel 7:25 prophesied -- "a time, times, and half a time." The Papacy reigns, persecutes the saints, and changes times and laws.
The deadly wound (1798 AD): Napoleon's General Berthier takes the Pope captive. The 1,260 years end. But the wound heals (Revelation 13:3) -- the Papacy recovers influence and continues to this day.
The most dangerous teaching in modern Christianity is the claim that the restrainer is the "Holy Spirit" and that it will be removed in a future "rapture." This teaching accomplishes exactly what the adversary wants: it makes you look to the future for something that has been operating for nearly 1,500 years.
If you are waiting for the "man of sin" to appear, you will never recognize that he has been sitting in the temple of Elohim (the church) since 538 AD, "shewing himself that he is Elohim" (2 Thessalonians 2:4) -- claiming to be the vicar ("substitute") of the Messiah on earth.
The restrainer was Pagan Rome. It was removed. The lawless one was revealed. He has been operating in plain sight for over a millennium. The only question is: do you have eyes to see it?
The futurist interpretation -- the idea that the antichrist is a single future individual -- was invented by Francisco Ribera, a Jesuit priest, in 1585 AD. Its sole purpose was to deflect the Protestant reformers' identification of the Papacy as the antichrist system. Before Ribera, virtually every Protestant reformer -- Luther, Calvin, Knox, Wesley, Tyndale, Huss -- identified the Papacy as the man of sin.
Today, nearly all of mainstream Christianity has adopted Rome's own counter-reformation interpretation. The reformers would weep.
The mystery of iniquity (apostasy) was already working in Paul's day.
The restrainer was Pagan Rome / the Caesars -- the power preventing the Papacy from rising.
The restrainer was removed in 476 AD when the Western Roman Empire fell.
The lawless one was revealed in 538 AD -- the Papal system with full authority.
This is not future. It has been fulfilled for nearly 1,500 years. Open your eyes.