Thomas Brooks emphasizes the power of assurance in Christ to keep believers from being overly attached to worldly desires and temptations. He illustrates this through the examples of Moses and Paul, who, grounded in their assurance of God's love and eternal reward, disregarded the fleeting glories of the world. Brooks argues that true assurance leads to a heart that is dead to worldly pursuits, as exemplified by Lazarus, who, after his resurrection, found no joy in earthly things. He calls for Christians to cultivate this assurance to avoid the dishonor of God and the reproach of the gospel. Ultimately, Brooks encourages believers to prioritize their communion with Christ over worldly glory.