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Once again we may ask—how is it that Jesus assumed an authority and reign that he did not previously possess? The answer is found in an important distinction. We may distinguish Jesus’ essential dominion or reign from his mediatorial dominion or reign. This is how Ebenezer Erskine and James Fisher, two eighteenth-century Scottish commentators on the Westminster Shorter Catechism, express the difference. Q. 17. How manifold is [Jesus’] kingdom? A. It is twofold; his essential and his mediatorial kingdom. Q. 18. What is his essential kingdom? A. It is that absolute and supreme power, which he hath over all the creatures in heaven and earth, essentially and naturally, as God equal with the Father, Psal. ciii. 19, “his kingdom ruleth over all—” Q. 19. What is his mediatorial kingdom? A. It is that sovereign power and authority in and over the church, which is given him as Mediator, Eph. i. 22.52
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