2 Don't be so easily shaken or alarmed by those who say that the day of the Lord has already begun. Don't believe them, even if they claim to have had a spiritual vision, a revelation, or a letter supposedly from us.
3 Don't be fooled by what they say. For that day will not come until there is a great rebellion against God and the man of lawlessness is revealed-the one who brings destruction.
Matthew Henry's Commentary on 2 Thessalonians 2:2-3
Commentary on 2 Thessalonians 2:1-4
(Read 2 Thessalonians 2:1-4)
If errors arise among Christians, we should set them right; and good men will be careful to suppress errors which rise from mistaking their words and actions. We have a cunning adversary, who watches to do mischief, and will promote errors, even by the words of Scripture. Whatever uncertainty we are in, or whatever mistakes may arise about the time of Christ's coming, that coming itself is certain. This has been the faith and hope of all Christians, in all ages of the church; it was the faith and hope of the Old Testament saints. All believers shall be gathered together to Christ, to be with him, and to be happy in his presence for ever. We should firmly believe the second coming of Christ; but there was danger lest the Thessalonians, being mistaken as to the time, should question the truth or certainty of the thing itself. False doctrines are like the winds that toss the water to and fro; and they unsettle the minds of men, which are as unstable as water. It is enough for us to know that our Lord will come, and will gather all his saints unto him. A reason why they should not expect the coming of Christ, as at hand, is given. There would be a general falling away first, such as would occasion the rise of antichrist, that man of sin. There have been great disputes who or what is intended by this man of sin and son of perdition. The man of sin not only practises wickedness, but also promotes and commands sin and wickedness in others; and is the son of perdition, because he is devoted to certain destruction, and is the instrument to destroy many others, both in soul and body. As God was in the temple of old, and worshipped there, and is in and with his church now; so the antichrist here mentioned, is a usurper of God's authority in the Christian church, who claims Divine honours.