Chuck Smith emphasizes the sovereignty of God in his sermon 'The Lord Reigneth,' illustrating the evidence of His reign through the universe, nature, and the intricate designs of creation. He addresses the question of why calamities exist if God reigns, attributing the world's ills to humanity's rebellion against God's authority. Smith reassures believers that despite the chaos, God is still in control, and His reign brings comfort and peace in our lives. He encourages personal acknowledgment of God's rule, which leads to a life of joy and assurance.