Zac Poonen emphasizes the distinction between two types of sins and blessings in his sermon. He explains that Adam's sin harmed only himself, while Cain's sin harmed others, highlighting that God takes the latter more seriously. Poonen urges believers to recognize the gravity of sins that hurt others, such as gossip and judgment, and to understand that true blessings come from being filled with the Holy Spirit to serve others, not just for personal gain. He calls for a shift in perspective within the church regarding the seriousness of different sins and the purpose of blessings. Ultimately, Poonen encourages believers to be channels of God's blessings to others, following the example of Jesus.