S. Lewis Johnson emphasizes the significance of the Great Flood and the Saving Ark in Genesis 7, illustrating Noah's unique righteousness and obedience to God's command. He highlights that Noah's faith and actions serve as a model for believers, showcasing the importance of responding to God's Word amidst ridicule and skepticism. The sermon draws parallels between the flood as a historical event and the salvation offered through Jesus Christ, underscoring the necessity of faith and obedience in the face of divine judgment. Johnson also discusses the implications of the flood for understanding God's sovereignty and grace in salvation, urging listeners to trust in the promises of God.