2 Thes 2 is about the coming of the Lord Jesus and how we will be gathered to Him. Paul warns of the preceding days of deception that will occur, when the "man of lawlessness" is revealed. This man will claim to be God and exalt himself and even sit in the temple of God. But the Lord Jesus will destroy him "by the splendor of His coming". All those who have refused to accept the gospel truth that would save them, will be greatly deceived into believing the lies of the "man of lawlessness". He will use every kind of evil deception to fool them and they will be condemned for enjoying evil, rather than believing the truth.
Paul , then gives thanks for the brethren chosen by God to experience salvation. He explains that they were called to salvation through the Spirit who makes them holy and through their belief in the truth, and by His grace they were given eternal comfort, a wonderful hope, and a future share in the glory of Jesus. What an encouragement that we, too, can share this same eternal comfort and hope in our future with Christ. Amen.