Mike Bickle discusses the theme of proven character in the life of David as he faces repeated tests of faith and integrity, particularly in the wilderness of Ziph where he has another opportunity to kill Saul but chooses not to. Bickle emphasizes that true character is not demonstrated by a single act of righteousness but through consistent choices over time, especially under pressure. He draws parallels between David's experiences and the greater example of Jesus, who entrusted Himself to God amidst slander and mistreatment. The sermon highlights that God desires a continual 'yes' from us in our walk of faith, and that failure is not the end, as God offers us chances to grow and learn from our mistakes. Ultimately, Bickle encourages believers to trust in God's leadership and to develop a deep-rooted value system that reflects His character.