David Wilkerson emphasizes the significance of understanding the joyful sound of Jubilee, which represents the freedom and deliverance provided through Jesus Christ. He explains that many Christians live in fear and confusion because they do not fully grasp the blessings that come from knowing this joyful sound. The sermon highlights that those who recognize this sound will walk in the light of God's presence, rejoice in His righteousness, find strength in Christ, and trust in the Lord as their defense against all enemies. Ultimately, the joyful sound is a proclamation of the victory and freedom believers have through the blood of Jesus.