"Now we request you, brethren, with regard to the coming of our Lord Jesus Christ and our gathering together to Him, that you not be quickly shaken from your composure or be disturbed either by a spirit or a message or a letter as if from us, to the effect that the day of the Lord has come. Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction, who opposes and exalts himself above every so-called god or object of worship, so that he takes his seat in the temple of God, displaying himself as being God. Do you not remember that while I was still with you, I was telling you these things? And you know what restrains him now, so that in his time he will be revealed. 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." (2nd Thessalonians 2:1-7)The peace of the church in Thessalonika had been disturbed by those who taught that the resurrection had already occurred, that Jesus had already returned, and that the millennial reign had already started. For some, these rumors had shaken their faith and left them wondering what to do. Paul wrote to reassure them that such had not happened and to quiet their spirits by reminding them of what he had previously taught them.
Teachings regarding the end of the age are common to many religions and cultures around the world, however, Jesus and His apostles made it clear that such events would not happen without our notice. Jesus taught us that, "just like the lightning, when it flashes out of one part of the sky, shines to the other part of the sky, so will the Son of Man be in His day." (Luke 17:24) The coming of the Son of Man will be an event not to be missed. It will not be some secret returning for His chosen but rather a returning that will be noticed by all who live at that time. "Behold, He is coming with the clouds, and every eye will see Him, even those who pierced Him; and all the tribes of the earth will mourn over Him." (Revelation 1:7) To this end, Jesus warned us to not be shaken by false claims or to run after false christs. "Behold, I have told you in advance. So if they say to you, 'Behold, He is in the wilderness,' do not go out, or, 'Behold, He is in the inner rooms,' do not believe them. For just as the lightning comes from the east and flashes even to the west, so will the coming of the Son of Man be." (Matthew 24:25-27) When Jesus comes again, everyone will know and see it.
As to the timing of His return, Paul tells us a couple of important indicators that must happen first. First, there will be a great apostasy, a falling away from faith and devotion to God. It is unclear if Paul was speaking specifically of the church or of nations and the world in general. Certainly, in our age, we are seeing an apostasy among many formerly Christian nations. It began in Europe, a continent steep in Christian history and tradition, and has spread to America and many other western nations. Previously, many would at least acknowledge God even if they themselves were not believers, but now there is a tidal wave of cultural revolution that is seeking to secularize every aspect of our lives. Even in Paul's day, most unbelievers were still religious and believed in gods, but today unbelief in even the existence of a god is spreading through out more and more of our society and culture. Truly we are living in a time of great apostasy.
Secondly, Paul tells us that, before that great day and the coming of our savior from heaven, the man of sin must first be revealed. Paul's description of the man of sin reminds me of the Roman emperor Titus who destroyed Jerusalem, set it on fire, and stood in the very temple of God; displaying himself as superior to the Jews and the God they worshiped. While he might not have called himself a god, he displayed himself as superior to the one true God who was worshiped by the Jews. To be God is to be supreme and to be above all others who claim themselves to be gods. Today we see the rise of personal cults and those who portray themselves as gods. We see this among some of the religious elites who draw followers after themselves. We also see this in charismatic world leaders who try and elevate themselves above the others; as the one truly wise and worthy ruler of the people. However, more than this, will be the character of this false christ. This man of sin will oppose all that is holy and righteous and true; leading people astray into unrighteousness and falsehood. Jesus said, "for the tree is known by its fruit." (Matthew 12:33) In that day, many will try to deceive us by their power and their signs and wonders, but it is by their fruit that we will know them. Those who come bearing the fruit of the Spirit are of the Spirit and those who come bearing the fruit of sin are of the devil.