The mediatorial kingdom refers to the specific domain of authority entrusted to Jesus Christ by the Father, in recognition of His redemptive work. Distinct from the natural sovereignty Christ shares eternally with the Father and the Holy Spirit, this kingdom is uniquely administered by Christ as the God-man, serving the redemptive purpose of reconciling humanity to God.
Scripture reveals that the Father bestowed this kingdom upon Christ as a reward for His sacrificial obedience (Psalm 2:8; Philippians 2:6-11). This bestowal underscores the covenantal relationship within the Trinity and the fulfillment of divine promises through Christ's mediation. The mediatorial kingdom is inherently spiritual, focusing on the redemption and sanctification of His people (John 18:36; Luke 17:20-21). While it encompasses all creation, its primary manifestation is within the church, where Christ reigns as Head, guiding and nurturing believers through His Word and Spirit (Ephesians 1:22-23).
This kingdom operates for the eternal salvation of its members, effectuating the application of Christ's redemptive work. Through the means of grace—such as the preaching of the Word, sacraments, and church discipline—Christ administers His rule, leading His people toward holiness and ultimate glorification (Ephesians 4:11-13). Although Christ possesses all authority in heaven and on earth (Matthew 28:18), His mediatorial dominion is exercised with a redemptive focus, orchestrating all events and authorities to serve the advancement of His kingdom and the good of His church (Romans 8:28; Ephesians 1:20-22).
It is crucial to distinguish between Christ's natural supremacy as the second person of the Trinity and His mediatorial dominion as the incarnate Redeemer. The latter pertains specifically to His role in the economy of salvation, wherein He acts as Prophet, Priest, and King for the benefit of His people (Hebrews 1:1-3). The mediatorial kingdom can be understood in two aspects. First, the kingdom of power refers to Christ's sovereign rule over all creation, directing all things for the sake of His church (Psalm 110:1-2). Second, the kingdom of grace describes His redemptive reign within the hearts of believers, cultivating righteousness, peace, and joy in the Holy Spirit (Romans 14:17).
The mediatorial kingdom will reach its consummation when Christ returns in glory, having subdued all His enemies. At that time, He will deliver the kingdom to the Father, and God will be all in all (1 Corinthians 15:24-28). This understanding aligns with historic Reformed theology, as articulated by theologians like John Brown of Haddington, who emphasized the comprehensive and redemptive nature of Christ's mediatorial dominion. Recognizing this kingdom encourages believers to submit to Christ's gracious rule, participate actively in the life of the church, and anticipate the ultimate fulfillment of His redemptive plan.