A.B. Simpson emphasizes that true victory begins with self-conquest, drawing parallels to Joshua's battle where Moses' uplifted arms symbolized reliance on divine strength rather than human effort. He highlights that spiritual triumph comes from being led by the Spirit, which empowers believers to overcome sin and live under grace. Simpson warns that internal struggles can hinder one's spiritual journey, as seen in Saul's life, and encourages believers to seek victory over their inner enemies to serve the Lord effectively. The sermon ultimately points to Jesus as the greater Joshua who enables us to achieve holiness and victory.