Barth brilliantly notes the links between Zizendorf, the quest, and the cult of the sacred heart of Jesus. All, he claims, involve a devotion to the human nature of Jesus as such.

Zizendorf’s preaching showed “peculiar interest in the creaturely sufferings of Christ.” And “we have here the precursor in method of the rationalistic portraits of Jesus later in the century.” And, “this undertaking finds its exact material and historical parallel in the Heart of Jesus cult,” which made the “whole Christ” the object of devotion but which distinguished this whole Christ from “objects of manifestation,” which were “the humanity of Christ and the parts of it in which the divine perfections are specially expressed.”

In contrast to all this, Barth insists that the humanity does not serve as revelation except insofar as it is the humanity of the Word, and thus the humanity “certainly cannot in itself, abstractly and directly, be the object of faith and worship.”