Nikolai F. S. Grundtvig is not known as an innovator. He's held out as a romantic and as cultural conservative. One way in which he is radical, perhaps without knowing it, is when he states that to be Christian is to be merely human. Or just human. Clint Schnekloth explored this a bit in a recent post.
And Grundtvig is even more powerful when he, like many throughout history, state that Jesus' divinity precisely in his humanity.
This means that there is no divine add-on, no hidden divine actor cooperating with a human partner. No quality or divine sheen that is the +1 that enhances Jesus.
As the truly human one, Jesus is as the crucified, one with God. It is not by being a certain thing or being sent in a certain way from the eternal pre-historical prom party that is the divine life that Jesus is God but by his history, by his actions, by his flesh-and-blood life that is truly human, love for others. He is the one in whom creation finds its fulfillement because he not only responds to the call creation and all creatures ask of one another but attends to the injury and pain of life. This is his divinity, his human solidarity and death, held together in a strange way by the resurrection in the Spirit.
The divinity is his humanity, meaning that to be divine is for God to be God in this Jesus, to have given up all divinity waiting on this Jesus and his fate, for them together to single out their Spirit and mutual love to be their future and utterly possibility.
In a way, this theologomenon is a kind of test. If you worry: adoptionism! arianism! monophysitism! You just might be perpetrating the kind of Jesus that is not truly human.
Worried about adoptionism? Jesus is truly human in his relation to God throughout his life -- there is no time in which he wasn't human. So goes adoptionism by the wayside.
Worried about arianism? There was when he was not? There is no Jesus pre-Jesus unless it is the stage of eternity and history clearing its way for Jesus to be conceived. Jesus' eternity is precisely his relation to God the Father. Does this make me go for some Barth election stuff? Perhaps. But the freedom in the Spirit, which is their future, is more eternal and important than all that election-pre-stuff to me.
Worried about monophysitism? Naw. Step aside. As Pannenberg and Jenson have it, the divinity is precisely in Jesus self-differentiation from God and God's self-differentiation from Jesus. Divinity is their eternal common life, not a thing that Jesus is.
Christians feel variously bound by ancient ways of talking. And I like it when there are theologomena that explode and shake up those ancient ways without utterly abandoning antiquity.
This is what Jenson calls the revisionary task of theology.