The sermon addresses the Thessalonian believers' discouragement regarding the fate of those who had died before Christ's return and the potential for divine wrath, offering comfort through the gospel. It emphasizes that believers should not grieve as those without hope, as the dead in Christ will rise first and be united with the Lord, and that believers are not alone but belong to Christ in life and death. The message encourages mutual support and reminds listeners that their ultimate comfort lies in communion with Jesus Christ, offering hope and assurance of eternal life with Him.