Pastor Nathan Francis's sermon "Repentance and Worship" focuses on Nehemiah 9, emphasizing the power of God's word to impact listeners. The sermon delves into worship, confession, repentance, and God's mercy, highlighting the importance of personal repentance and confessing sins for revival. By emphasizing the pattern of acknowledging God's greatness leading to worship and repentance, Pastor Francis urges the congregation to seek God's forgiveness and mercy through personal repentance and confession.