The sermon examines the story of Cain and Abel to illustrate the pervasive nature of sin and the necessity of God's grace. It highlights Cain's failure to respond with repentance after committing murder, contrasting his actions with Abel's offering and emphasizing the importance of recognizing one's own iniquity as greater than one can bear. The message underscores God's sovereignty, the need for continual cleansing of sin through discipline and discipleship, and ultimately, cherishing Christ's gift of salvation as the only means of reconciliation and enduring grace, demonstrating that even in the face of profound failure, God provides a path to redemption and a renewed relationship.