Barth is exploring the relationship between divine essence and human essence in the hypostatic union. He examines a particular form of the Lutheran communicatio idiomatum which, for all the qualifications presented, appears to him to amount to a divinising of the humanity of Christ. However, since the human nature of Christ is the human nature of all humankind, then surely the door is opened to a general divinisation.
But where does the way through this door lead? It obviously leads smoothly and directly to anthropology: ... to the doctrine of a humanity which is not only capable of deification, but already deified, or at any rate, on the point of apotheosis or deification.
And then the uniqueness of Christ is lost and humanity may be worshipped:
If the supreme achievement of Christology, its final word, is the apotheosised flesh of Jesus Christ, omnipotent, omnipresent, and omniscient, deserving of our worship, is it not merely a hard shell which conceals the sweet kernel of the divinity of humanity as a whole and as such, a shell which we can confidently discard and throw away once it has performed this service?
And then we might conclude, says Barth, that it is not an accident that German Idealism grew up in the soil of this Lutheran doctrine.
For does not this correspond more or less exactly to the anthropology which is so easily reach from this Christology once its open door is passed – the anthropology of a humanity which is destined and able to be deified, and already on the point of deification? ... Was Hegel so wrong after all when he thought that he could profess to be a good Lutheran?His conclusion – and I am not at all sure that in a chain of argument so long as this (Barth takes 11 pages to work this out) the conclusion is inescapable – is that
Luther and the older Lutherans did in fact compromise – at a most crucial point – the irreversibility of the relationship between God and man, long before the message of the Church was similarly affected by a secular human self-understanding ...And he then reflects,
We cannot toy unpunished with inversions of this type ...