3 The Personal Union
The human nature of Christ has been assumed into the person of God the Son. This is the personal union - one person despite a divine and a human nature. This is not union only in activity. It is a closer unity than that of Christ and his believers. God the Son is truly God. God is in Christ in such a way that Jesus, the human, is divine. Pieper discusses a number of metaphors often used for the two natures of Christ, showing that none can live up to the genuine unio personalis.
Was Jesus aware of this? In location 1924 Pieper asserts that Jesus knew he was both divine and human. This, however, is not widely accepted. “At all times men, without and within the pale of the Christian Church, have been looking for substitutes for the hypostatic union” (Loc. 1940). Pieper gives examples of attempts to replace this doctrine, all of which fall short of Scripture. His conclusion is that “The salvation of the world could be effected only through the theanthropic work of Christ, and that required a theanthropic Person” (Loc. 1960).
Pieper continues with an analysis of various substitute theories (Loc. 2008 ff).
First, “The union between God and man in Christ is not a nominal union” (2008). The name of God is simply symbolic.
Second, “It is not a union habitualis, relativa, signifying merely a close relationship” (Loc. 2015).
Third, “It is not a unio acidentalis, an external, accidental union” (Loc. 2023).
Fourth, “It is not a union sustentiva, consisting in the mere presence and sustaining power of God” (Loc. 2031).
Fifth, “It is not a unio naturalis. We speak of a natural union in the case of things which have a natural relationship to each other” (Loc. 2035).
Sixth, “It is not a unio essentialis or commixtiva.” (Loc. 2060).
Finally, “The personal union is not a unio per adoptionem” (Loc. 2101).