Who is the lawless one/Man of Lawlessness (2 Thessalonians 2:8-9) and antichrist(s) (1 John 2:18-22, 1 John 4:3, 2 John 1:7)?
B. Hodge, Biblical Authority Ministries, June 18, 2020
Many equate the lawless one with “The Antichrist” (and even the beast of Revelation). Though, this is not without warrant as the man of lawlessness would be an antichrist by definition.
It was John that mentioned antichrist(s) exclusively (1 John 2:18-22; 1 John 4:3; 2 John 1:7). An antichrist is anyone who denies that Jesus is the Christ or that Christ has not come in the flesh; in their denial of the Son, they also deny the Father (1 John 2:22, 1 John 4:3). According to John, the spirit of the antichrist was already in the world (1 John 4:3) in his day.
Many had reported to John that the antichrist was coming and John pointed out that it was the last hour and many antichrists had already come/appeared. Perhaps they had missed or overlooked them. So what we can learn is that there are many antichrists and perhaps one specific one is in mind in this passage. So, the man of sin was an antichrist with little doubt.
Man of Lawlessness/Man of Sin
In 2 Thessalonians 2:1-12, Paul points out that the “man of sin” or “lawless one” was being restrained, would be revealed, would fall away, and be destroyed. It was clearly a man living at the time of Paul’s writing (vs. 6-7) and the coming of the Lord (in judgment which happened in A.D. 70) would not occur until these things Paul penned had come to pass. This limits the man of lawlessness to a timeframe prior to A.D. 70.
But let’s consider the very basis of the name: “lawless” one. Who was the only person in the known world at the time of Paul’s writing to the Thessalonians who was not bound to any law? It was the emperor of Rome (i.e., the beast of Revelation). Such a ruler was the law, or more appropriately, above the law and acted as such. Of course, this is inherently a rebellion against God and His Law (1 Timothy 1:9-11). But this makes the emperor a man of sin, since he opposed the law of God.
The identity of the man of lawlessness would be another name for that of Nero Caesar (Nero Claudius Caesar Augustus Germanicus) who reigned from A.D. 54-68 to be precise, whose actions were actually quite favorable to Christians initially. Paul even appealed to Caesar in Rome, to which, he was acquitted (beginning in Acts 25:11) by Nero. Even Christians were in Nero’s own household (Philippians 4:22).
There was a change in Nero, where his rage turned against Christians in A.D. 64. He blamed them for burning Rome, though it was likely set by Nero himself, as attested to by several including Tacitus, a senator and historian of Rome. Keep in mind that the mind of an unbeliever is blinded and not able to discern a proper understanding of biblical things (e.g., John 12:40, Romans 1:18-28, Romans 11:7-25, 2 Corinthians 3:7-16, 2 Corinthians 4:4, Ephesians 4:17-19, Titus 1:15-16, 2 Timothy 2:23-26).
Paul was again imprisoned and ultimately killed by Nero in A.D. 68 by being beheaded as afforded from testimony such as early Christian historian Eusebius. After killing Peter and Paul and many other Christians in violent and unspeakable ways, this set the stage for both Roman persecution of the church and unleashed the Jewish persecution to be unrestrained by Rome as well. He was permitted to do this for 42 months (Revelation 13:5). Nero committed suicide later in A.D. 68 (after Paul was killed) after three and half years (interestingly, this is 42 months) of intense blasphemies and persecution; and so he was destroyed.
Nero was in the world at the time, being restrained, revealed, fell away, and was destroyed. Nero’s comparison with the description of the man of lawlessness is striking.
Re-read 2 Thessalonians 2:1-12.
 Note the recipients of the letter knew that the coming of the Lord was not the end of the world/last day for they were already distressed that the coming had already taken place! And clearly, the world hadn’t ended. It is in the context of judgment as many other “comings” of the Lord.
 Eusebius, Hist, Eccles. lib. ii. cap. 25