Paul turns to the day Jesus returns and gathers His people to Himself. The believers had been shaken by a message, perhaps claimed to be a letter from Paul, claiming that the day of Christ was already here. Paul writes: Let no one deceive you in any way. He urges them not to be quickly shaken in mind or troubled.
Paul explains that the day will not come until the rebellion comes first and the man of sin is revealed. This lawless one sets himself up against God and everything that is worshiped. Paul reminds them that he had told them these things in person. The mystery of lawlessness is already at work, but it is being restrained for now. When the lawless one is revealed, the Lord Jesus will destroy him by the appearance of His coming. Those who refused to love the truth will be deceived.
But Paul gives thanks for the believers, whom he calls brothers loved by the Lord. From the beginning God chose them to be saved, as the Spirit made them holy and they believed the truth. He called them through the Good News, to obtain the glory of our Lord Jesus Christ. Paul's command is clear: stand firm and hold the traditions which you were taught by us, whether by word or by letter. He prays that our Lord Jesus Christ and God our Father, who gave eternal comfort and good hope through grace, will encourage them and make them strong in all they do and say.