The sermon centers on the profound significance of Christ's sacrifice as a penal substitute for humanity's sins, drawing heavily from 1 Peter 3:18, Isaiah 53, and Leviticus 16 to illustrate the necessity of atonement and the fulfillment of divine justice. It emphasizes the concept of substitutionary sacrifice, where Christ, the righteous one, bore the penalty for the unrighteous, offering a once-for-all offering that secures pardon and transfers righteousness to believers. The message underscores the importance of understanding Christ's work not only as forgiveness but also as the provision of a righteousness that enables believers to approach God, ultimately highlighting the transformative power of the gospel and the assurance of freedom from condemnation through faith in Christ.