Again, because this is important, in evangelical Calvinist theology, After Barth and After Athanasius, the work, the being and reality of salvation cannot be separated from the person of Christ (and the unio personalis). That said, how is the integrity of humanity simpliciter maintained if all of salvation is accomplished in the humanity of Jesus Christ as a prius? Following Barth, this
is something I affirm as an evangelical Calvinist; it is the Holy Spirit, the same Holy Spirit who overshadowed Mary, and the same Holy Spirit who did the work of salvation in the humanity of Christ, who works that salvation into humanity after the new/re-created humanity of Jesus Christ.
The following is a quote (a short one compared to my last post) that elucidates how this transitioning work looks from the humanity of Christ to the remaining humanity (or ours). The link is made between Barth and Athanasius at this point; you’ll see why:
We must further note that there are strong parallels between Barth’s development of the necessity of the identity of the Spirit as the Spirit of the Lord and the Athanasian development of the soteriological necessity of the hypostatic union. For Athanasius, if Jesus Christ is not fully God, he could not save us, for divine presence and power is indispensable to salvation. Likewise, if Jesus Christ is not fully human, he could not save us, for full and effective comprehension of human being is also necessary to salvation. In similar fashion, in Barth’s construal of this transition, if it is not genuinely the Spirit of Jesus Christ who comes to us, how can we be encountered by our new reconciled human being as it is in Jesus Christ? Moreover, if the selfsame Jesus Christ does not come to us, how can we be saved? The transition from Jesus Christ to others must be the radical encounter of Jesus Christ himself (not a tertium quid) and us others. Only in the Holy Spirit, the Spirit of the Lord, is this possible.
Looking to the New Testament, Barth concludes that the solution given there to the problem of the distance between Jesus Christ in his crucifixion and us, and of the transition from him to us, is ‘[t]he outpouring of the Spirit as the effect of His resurrection, of His life in His death and in the conquest of His death, and therefore the occurrence of His self-impartation.’ On Barth’s reading of the New Testament, the holiness of the Holy Spirit is to be understood as:
the fact that He is the self-expression of the man Jesus, and that as such He is Himself His effective turning to us and our effective conversion to Him; His disclosure for us and our disclosure for Him; and, as this comes to us in this twofold sense, the new thing in earthly history.
Whatever else we might be said concerning the Holy Spirit, we cannot moderate the claim of the identity of the Spirit as the Spirit of the Lord, without sacrificing the genuine transition of reconciled human being and action from Jesus Christ to others.
It is the whole Christ, both fully God fully man/human who we require to save us. It is in this hypostatic union wherein salvation is fully accomplished in Christ. In his humanity (theanthropos) what it means to be human before God has become fully actualized and realized, and this for all of humanity. Jesus’s yes to God, means that all humans can now say yes to God, from Christ’s (as the mediating and archetypal human). But, how does this work its way into the rest of humanity without violating what it means for the rest of humanity to be personal agents? By the Holy Spirit.
We will have to leave this here for now. I just wanted to share this quote with you because it fits well with my last post.
 Robert Dale Dawson, The Resurrection in Karl Barth (Burlington, VT: Ashgate Publishing Company, 2007), 150-51.