Like anything worth knowing about, Christianity has a set of terms that are basically unique to it – terms like hypostatic union, the union of divine and human natures in the one person of Jesus, or perichoresis, the divine mutual indwelling of members of the Trinity. Christianity of course also has unique understandings of more common terms, such as faith being about trust and reliance not just intellectual assent or believing in the absence of evidence, or propitiation not being an activity where humans appease an angry God but uniquely where God himself appeases his own wrath.
Two important Christian technical terms are anhypostasia and enhypostasia, which are both Christological terms relating specifically to the incarnation. It’s relatively simple to explain what these two terms are refering to:
anhypostasia: means literally “not-person” and refers to the fact that there was no independent human person which the divine Son entered into or took over. The human nature of Jesus never existed apart from the incarnation of the Logos as a human. In the incarnation God the Son did not take on a genuine human person but rather a genuine human nature.
enhypostasia: means literally “in-person” and seeks to affirm that the Logos did not just relate to us through a general humanity but became a specific individual, the man Jesus. And this human Jesus, possessing genuine human nature, was with regard to his personhood the Second Person of the Trinity. That is to say, from the first moment that his human nature existed it was in hypostatic union with his divine personhood. From the first moment his human nature existed it has its personhood in the personhood of God the Son. Enhypostasia is seeking to preserve the true, historical, specific humanity of Jesus. Anhypostasia is seeking to preserve the general humanity of Jesus.
To put it another way, anhypostasia emphasises that God himself became one of us humans, whereas enhypostasia emphasises that God himself became one of us humans.
And ofcourse anhypostasia and enhypostasia must always come together and are really two parts of one concept, with enhypostasia flowing out from anhypostasia and then back into it.
What the one concept helps us understand is how Jesus could take upon himself our fallen humanity without himself then being a sinner. There was the anhypostatic taking on of fallen human nature, but with the enhypostatic purity of the Son.
All this is simply the prologue to TF Torrance’s quote on the place and role of technical Christian terms:
“All technical theological terms such as [anhypostasia and enhypostasia] are to be used like ‘disclosure models’, as cognitive instruments, helping us to allow the reality of Christ to show through to us more clearly. As in natural science we must often cast our thought about certain connections into mathematical or algerbraic form in order to see how those connections work out in the most consistent and rigorous way, so here we may think of ‘anhypostasia and enhypostasia’ as a sort of ‘theological algebra’ to help us work out the ‘inner logic’ in christology more consistently and purely. But once we see the connections more clearly in this way, they have to be translated back into ‘the flesh and blood’ or reality, translated back into terms of the person and work of Christhimself. Just as in a natural science, we may have to resort to algebra to work out the connections using algebra like a computer as it were, to compute for us what our brains are incapable of doing by themselves, but must then translate the algebra back into ‘physical statements’ in order to discern the real relations in empirical reality, so we must do much the same here. Anhypostasia and enhypostasia together do not contain the ‘stuff’ of christology, but they may be, rightly used, theological instruments or lenses through which we may discern more deeply or clearly the ontological structures of the incarnation.”
TF Torrance, Incarnation, p. 233