A.B. Simpson emphasizes the duality of human insufficiency and Christ's all-sufficiency, asserting that recognizing our helplessness is essential for spiritual growth. He explains that the Old Testament highlights human failure, while the New Testament reveals Christ's ability to meet all our needs. Simpson encourages believers to renounce their own perceived perfection and embrace Christ's righteousness, which leads to a deeper understanding of grace. He warns that acknowledging our insufficiency must be coupled with a firm faith that claims all that Christ offers. The sermon concludes with a call to humility and a full acceptance of God's greatness and grace.