Art Katz emphasizes the Apostle Paul's vehement opposition to legalism, particularly in his letter to the Galatians, where he warns against adding the Law to faith in Christ. Paul understood that any attempt to achieve righteousness through the Law contradicts the purpose of Jesus' sacrificial death, which was to condemn the flesh and self-righteousness. His personal encounter with the resurrected Christ on the road to Damascus profoundly shaped his understanding of grace and the necessity of seeing the death of Jesus as a complete atonement for sin. Katz argues that this revelation is crucial for believers today, as any return to self-righteousness undermines the grace of God and the sufficiency of Christ's sacrifice. The sermon calls for a deeper understanding and appropriation of the atonement to avoid making the grace of God ineffective.