“It is the crucified but also the resurrected and exalted Christ whom the apostles proclaim. From that vantage point of the exaltation of Christ, they view and describe His earthly life, suffering, and death.
For the work He now carries out as the exalted mediator, He laid the foundations in His cross. In His battle with sin, the world, and Satan, the cross has been His only weapon.
By the cross He triumphed in the sphere of justice over all powers that are hostile to God. But in the state of exaltation, consequently, He has also been given the divine right, the divine appointment, the royal power and prerogatives to carry out the work of re-creation in full, to conquer all His enemies, to save all those who have been given Him, and to perfect the entire kingdom of God.
On the basis of the one, perfect sacrifice made on the cross, He now—in keeping with the will of the Father—distributes all His benefits. Those benefits are not the physical or magical aftereffect of His earthly life and death; the history of the kingdom of God is not an evolutionistic process.
It is the living and exalted Christ, seated at the right hand of God, who deliberately and with authority distributes all these benefits, gathers His elect, overcomes His enemies, and directs the history of the world toward the day of His parousia.
He is still consistently at work in heaven as the mediator. He not only was but still is our chief prophet, our only high priest, and our eternal king. He is the same yesterday, today, and forever.
There is, of course, an enormous difference between the work Christ did in His humiliation and what He accomplishes in His exaltation. Just as after the resurrection, His person appeared in another form, so also His work assumed another form.
He is now no longer a servant but Lord and Ruler, and His work is now no longer a sacrifice of obedience, but the conduct of royal dominion until He has gathered all His own and put all His enemies under His feet.
Nevertheless, His mediatorial work is continued in heaven. Christ did not ascend to heaven in order to enjoy a quiet vacation at the right hand of God, for, like the Father, He always works (John 5:17).
He went to heaven to prepare a place for His own there and to fill them here on earth with the fullness that He acquired by His perfect obedience. What He received as a reward for His labor for Himself and what He received for His own cannot be separated. He is all and in all (Col. 3:11).
The pleroma (fullness) that dwells in Christ must also dwell in the church. It is being filled with all the fullness of God (Eph. 3:19; Col. 2:2, 10).
It is God whose fullness fills Christ (Col. 1:19), and it is Christ whose fullness in turn fills the church (Eph. 1:23). The church can therefore be described as His pleroma, that which He perfects and gradually, from within Himself, fills with himself (Eph. 4:10), and is therefore itself being filled by degrees.
As the church does not exist apart from Christ, so Christ does not exist without the church. He is ‘the head over all things’ (Eph. 1:22; Col. 1:18), and the church is the body (σωμα) formed from Him and from Him receives its growth (Eph. 4:16; Col. 2:19), thus growing to maturity ‘to the measure of the full stature of Christ’ (Eph. 4:13).
The union between Christ and the church is as close as that between the vine and the branches, between bridegroom and bride, husband and wife, cornerstone and building.
Together with Him it can be called the one Christ (1 Cor. 12:12). It is to perfect the church that He is exalted to the Father’s right hand.
Just as through His suffering and death Christ was exalted in His resurrection and ascension to be head of the church, so now the church has to be formed into the body of Christ.
The work of the Mediator is one grand, mighty, divine work that began in eternity and will only be completed in eternity.”
–Herman Bavinck, Reformed Dogmatics: Sin and Salvation in Christ, vol. 3, Ed. John Bolt, and trans. John Vriend (Grand Rapids, MI: Baker Academic, 2006), 473–475.