The sermon centers on the assurance of salvation, emphasizing that once Christ saves, that transaction is complete and cannot be undone, regardless of subsequent sins. Drawing from passages in 2 Corinthians and Romans, the speaker explores the spiritual death and subsequent resurrection believers experience, highlighting that Christ's work frees individuals from the dominion of sin and empowers them to live righteous lives, grounded in the unchanging truth of God's grace rather than legalistic adherence to rules. The message encourages listeners to reckon themselves dead to sin and alive to God, embracing their new identity in Christ and actively participating in sharing the gospel, ultimately resting in the security of God's unwavering love and provision.