Paul’s second letter to the Thessalonians is essentially an explanation of the end times, meant to convince them that the Rapture hasn’t occurred yet. In the first chapter he tells them that the Lord has promised the righteous salvation.
2 Thessalonians 2
Paul describes the end times, including the Rapture, the great apostasy, and the coming and reign of the Antichrist.
2 Thessalonians 3
Paul ends this epistle encouraging the Thessalonians to keep at it regardless of the challenges they face.