The sermon establishes the theological foundation of the believer's priesthood by tracing the concept of the firstborn from Old Testament figures like Jacob and Joseph to the New Testament reality of Christ as the firstborn among many brethren, emphasizing His preeminence and the inheritance of all believers. It highlights how God initially designated the firstborn sons of Israel as priests, later transferring that role to the Levites as a foreshadowing of the universal priesthood of all believers in Christ. Through passages in Romans, Colossians, and Hebrews, the message affirms that believers are joint heirs with Christ, sharing in His kingship and priestly authority, particularly in the millennial reign, where the last shall be first. The parable of the laborers in the vineyard illustrates divine grace and equity in salvation, affirming that all who come to Christ, regardless of when they believe, receive the same eternal inheritance. Ultimately, the sermon calls the church to embrace its priestly identity with responsibility, to stand in the gap against spiritual compromise, and to live in faithful stewardship of the divine calling.