In Jamie's sermon, he explains that being "poor in spirit" is a matter of the heart that Jesus Christ emphasized, encouraging believers to recognize their spiritual poverty and need for God's grace. Jamie illustrates this through biblical examples, showing that an encounter with God reveals a person's own sinfulness and leads to true humility. He concludes by urging Christians to adopt this mindset, countering the world's disdain for humility and reflecting a life transformed by understanding one's complete reliance on God.