Why did the Thessalonian believers think they had missed the rapture and were in the tribulation?
The Thessalonian believers thought they had missed the outcalling, or rapture, and were already in the tribulation because they were enduring intense persecution. Their suffering convinced them the gathering unto Christ had occurred without them, so Paul wrote to calm their fears and assure them they had not missed it.
Les explains that Paul wrote to the Thessalonians, Gentiles in northern Greece, concerning the coming of the Lord Jesus Christ and the gathering together unto Him. This language, he notes, is not the second coming, because there is no gathering unto Him at the second coming; Christ coming for the church is different. The Thessalonian believers evidently thought they had missed what is called the outcalling, or the rapture, and that they were in the tribulation because they were going under intense persecution. Paul therefore wrote this little letter to calm their fears and let them know they had not missed it. Les also illustrates how believers today can have a similar fear if loved ones suddenly seem gone, wondering, “Has the Lord taken them and I missed it?”
Now we beseech you, brethren, by the coming of our Lord Jesus Christ, and by our gathering together unto him,