David Wilkerson emphasizes the importance of faithfulness in handling what belongs to God, as Jesus teaches that our bodies and souls are not our own but purchased by His blood. He challenges believers to examine their hearts and deal with hidden sins before expecting greater faith or revelations from God. Wilkerson explains that Jesus' call to pluck up the roots of evil within us is essential for spiritual growth and effectiveness in faith. The sermon highlights that even a small amount of faith can lead to significant spiritual breakthroughs if we are diligent in our personal sanctification.