Now we request of you, brethren, concerning the coming of our Lord Jesus Christ and our gathering together near Him, you are not to be quickly shaken from the mind, nor to be troubled either through a spirit or through a word or through a letter as through us, as that the day of Christ has already arrived, 2 Thessalonians 2:1–2.
The day of the Christ, in this context, refers to the coming of Christ for His Church. We are not yet in the Millennial Kingdom, for Christ has not returned for His Church, nor has the Tribulation occurred. Before His second coming to earth, He will call His Church to meet Him in the air, for she is not appointed to any quality of wrath (1 Thessalonians 5:9).
We are not to be shaken in mind by those who claim that this day has already come, as though we had missed the day of Christ. We are not of the night nor of the darkness; therefore, the day of the Lord will not overtake us (1 Thessalonians 5:4).
There is a textual issue in this passage. Some translations, such as the ESV, render it “the day of the Lord.” However, upon examining the manuscript evidence, the phrase is either “the day of Christ” or “the day of the Lord Jesus.” Although stronger support exists for “the day of Christ,” either expression differs from “the day of the Lord,” which refers to the time when the kingdom of the heavens is established on earth and encompasses His second coming, Joel 2:31; 2 Peter 3:10; Acts 2:20.