New Defender's Study Bible Notes
2:3 falling away. The “falling away” (Greek apostasia) has commonly been transliterated as “the apostasy” (the definite article in the Greek indicates Paul had already told them about it), and then assumed to apply to the final great religious apostasy at the end of the age. The context, however, as well as the etymology of the word itself, makes this interpretation unlikely. In this precise form it is used nowhere else in the New Testament, so its meaning must be defined by its context here. It is derived from two Greek words, apo (meaning “away from”) and stasis (meaning “standing”). It thus could properly be rendered “standing away” instead of “falling away.” In Paul’s previous letter, he had made no reference whatever to a coming departure from the faith, but he had discussed at length a coming departure from the earth by all believers, when Christ returns to meet them in the air (I Thessalonians 4:13-18). Thus this “standing away from,” in context, seems to refer to all the raptured believers standing away from the earth, as they stand before their returning Lord when they meet Him in the heavens. Paul here is simply reminding them that the “sudden destruction” that would come upon unbelievers when “the day of the Lord” begins could not happen until the rapture—“the standing-away” from the earth before Christ (note Romans 14:10)—had taken place. The entire context, before and after, fits this understanding of the text better than the idea of the apostasy from the faith. Over the 1950 years since Paul wrote these lines, there have been numerous great apostasies form the faith, and none of these introduced the day of the Lord, although persecuted believers in each case might easily have so interpreted them.
2:3 man of sin. “The man of sin” is also called “the son of perdition” because of his being so fully energized and controlled by Satan that he is, in a unique way, the son of the devil. Judas, who was a type of this evil man, was also called “son of perdition” (John 17:12; note also Luke 22:3; John 6:70). The same person is also called “antichrist” (I John 2:18), “the prince that shall come” (Daniel 9:26) and various other names, but especially “the Beast” (Revelation 13:1,18, etc.). According to this verse, his identity will only be revealed after the rapture has taken place (note also II Thessalonians 2:7-9). Soon (perhaps immediately) thereafter, the great day of the Lord will begin on earth, while the day of Christ is also under way in the heavens. See notes on I Corinthians 3:13-15; Revelation 4:1-11.