“It is specifically Christ who is appointed by the Father to bring about the end of the history of humankind and the world. And He is appointed to this role because He is the Savior, the perfect Savior. The work He completed on earth is only a part of the great work of redemption He has taken upon Himself.
And the time He spent here is only a small part of the centuries over which He is appointed as Lord and King. Anointed by the Father from all eternity, He began to engage in His prophetic, priestly, and royal activity immediately after sin came into the world. He continued that activity throughout all the revolving centuries since.
And one day, at the end of the times, He will complete it. That which He acquired on earth by His suffering and death He applies from heaven by His word and the working of His Spirit; and that which He has thus applied, He maintains and defends against all the assaults of Satan, in order one day, at the end, to present it without spot or wrinkle, in total perfection, to His Father who is in heaven.
Accordingly, the return of Christ unto judgment is not an arbitrary addition that can be isolated from His preceding work and viewed by itself. It is a necessary and indispensable component of that work. It brings that work to completion and crowns it.
It is the last and highest step in the state of His exaltation. Because Christ is the savior of the world, He will someday return as its judge.”
–Herman Bavinck, Reformed Dogmatics, Volume 4: Holy Spirit, Church, and New Creation. Ed. John Bolt and Tr. John Vriend (Grand Rapids, MI: Baker Academic, 2008), 685.