"Equipping God's People to Reap the Harvest"
In Paul’s first letter to the Thessalonians, he encourages them to keep looking for the Second Coming of Jesus Christ. Some misconstrued this teaching to mean that Jesus would return almost immediately.
So in 2 Thessalonians, Paul corrects this idea and tells the people that before Christ comes again there will be a great apostasy or falling away, and that the man of sin (or antichrist) must appear.
Finally, Paul urges the Christians to remain faithful to Christ, in spite of suffering, and not be misled by false teachings about the Second Coming of Jesus.