Rev. Dr. Jack Whytock's sermon focuses on Jude 20-21, emphasizing the contrast between two kinds of people: the ungodly who cause divisions and the believers who are growing in faith. He highlights Jude's call for believers to build themselves up in the faith, pray in the Holy Spirit, keep themselves in God's love, and wait for the mercy of the Lord Jesus Christ.  

The sermon delves into the importance of personal responsibility for spiritual growth, emphasizing that while salvation is God's work, believers must actively engage in building upon the foundation of their faith. This involves knowing the gospel, sound doctrine, and God's commands, and actively applying them in one's life.   

Furthermore, the sermon emphasizes the importance of prayer in the Holy Spirit, which is characterized by spiritual focus, dependence on God, and allowing the Spirit to guide one's desires. It also highlights the need to meditate on God's love and to maintain an eternal perspective, looking forward to the mercy of Christ and the future glory.