Zac Poonen emphasizes the significance of sanctification, particularly the need for a pure spirit in our relationship with God. He highlights that true worship must come from the spirit, not merely from outward actions, and that maintaining a pure spirit is essential for experiencing God's presence and guidance. Poonen warns against the dangers of prioritizing work over worship and stresses that sanctification is God's work in us, requiring our submission. He encourages believers to cultivate a deep, intimate relationship with God, which will lead to discernment and a life that reflects His holiness.