In 2 Thessalonians 2 Paul addresses a misunderstanding about the return of the Lord and “our gathering” to him (2:1). The church is unsettled and alarmed over a report appearing to come from Paul himself claiming the Day of the Lord had already happened. It is possible this rumor refers to Caligula’s order to erect an image of himself in the Temple in Jerusalem, but this is not at all certain.
Whatever the case, their concern is no small thing. To be unsettled is the verb σαλεύω and is often used literally to described an earthquake or the movement of the sea. Here it is figurative for the disturbance that the Thessalonians are experiencing. They are not only shaken but also “alarmed” (θροέω). This is rare word in biblical literature, although in classical Greek it has connotation of being frightened or “crying out in surprise. The only place the word appears in the New Testament is in the Olivet Discourse (Matt 24:6/Mark 13:7). In a very similar context to 2 Thessalonians, Jesus warns the disciples not to be alarmed by “wars and rumors of wars” or other alleged “signs” the end is near.
The word for the coming of the Lord is παρουσία, the most common word for the return of Christ. The noun simply means “presence” or “arrival” and is used in a variety of ways. It can refer to the arrival of a human (Paul in 2 Cor 7:6), but it is also used for the visit of a person of high ranking, such as a king (3 Macc 3:17). This use usually included flattery, tributes, delicacies, transportation, and gifts of golden wreaths or money. If a god was active in history helping a human that presence of the god is called a παρουσία. Josephus uses the word to describe God’s presence in helping Israel (Antiq. 3.80). The word is used often in connection with sacred events where the presence of a god is assumed.
Paul uses this word not only to refer to the presence of Jesus, but also of the Man of Lawlessness (the Anti-Christ and has his own anti-parousia). The word can be stretched to cover all of the events associated with the eschatological age, similar to the “day of the Lord” in the Hebrew Bible. The second word, “gathering” is ἐπισυναγωγή, is quite rare in the New Testament, used only here and in Hebrews 10:25 where it refers to the gathering together of believers for worship. It is likely Paul is referring to the Rapture, using similar terminology to 1 Thessalonians 4:13-18.
There are a number of Old Testament passages that teach that Israel will be re-gathered prior to the Messianic kingdom. For example, in Isa 43:4-7 God gathers the children of Zion from the east, west, north, and south, a clear reference to Jews living in the Diaspora. When the eschatological age begins, God will gather his elect (the chosen) from the four winds and bring them back to Zion. (Compare this to LXX Isa 52:12, God is the “gatherer of Israel.” See also Isa 56:8; Jer 31:8. Ezek 20:34; 34:16, Ps 106:47.)
This noun is used in the Second Temple Period for the gathering of Israel at the beginning of the eschatological age. In 2 Macc 2:7 the secret place where the Ark is hidden will not be revealed until “God gathers his people again” (using the verb συνάγω and the noun ἐπισυναγωγή). The word also appears in T.Naph 8:3 where it describes the gathering of the righteous out of the nations at the beginning of the eschatological age. Similarly, T.Ash 7:7 the Lord will gather Israel on account of Abraham, Isaac and Jacob.
The idea of Israel being re-gathered is the point of Jesus’ words in Matt 23:37 / Luke 13:34. Jesus contrasts God’s desire to gather Israel together under his wings with their rejection of him as the Messiah. A bit later in the Gospels Jesus uses the noun to describe the gather of the elect from the four winds when Messiah judges the world (Matt 24:31). In fact, in Matthew there is a loud trumpet call that draws the elect from the four corners of the world. The parallel is not precise, however, since Jesus is referring to the gathering of Jews in dispersion together just prior to the establishment of the kingdom. Paul is addressing a Gentile congregation
It is better, therefore, to see Paul’s use of the word as an extension of the Jewish idea of a gathering together prior to the coming of Messiah. Prior to the Day of the Lord there will be a “gathering” (described more fully in 1 Thessalonians 4:13-18). Even though Paul’s description of this gathering is unique in Jewish literature, he is using apocalyptic imagery to describe the “end of the age.”
One application of this line of thinking should be to de-emphasize the tendency among (mostly conservative) Christians to predict the date of the Rapture or to claim that a given even fulfills prophecy, or to declare some world figure is the antichrist. Although there is an attraction to these sorts of religious conspiracy theories, both Jesus and Paul would say “do not be alarmed” at these non-signs of the end.