It’s interesting to read how Barth perceived, and blasted, the historical Jesus project at his time, as I think what he observed at his day still holds true today:
“The so-called historico-critical method of handling Holy Scripture ceases to be theologically possible or worth considering, the moment it conceives it as its task to work out from the testimonies of Holy Scripture (which does ascribe to revelation throughout the character of miracle), and to present as the real intention, a reality which lacks this [miraculous] character, which has to be regarded as reality otherwise than on the basis of God’s free, special and direct act.
This must be said particularly of the gigantic attempt (still as gigantic as ever) of the “Life of Jesus research”, i.e., the attempt, made in every style from mildest conservatism to the most imaginative or else most unimaginative, “hypercriticism”, to uncover out of the New Testament, by means of a series of combinations, restorations and also and particularly deletions, the figure of the mere man Jesus, the so-called “historical Jesus”, as he might have lived in the years 1-30. In this way he might be presented as an enthusiast well-nigh deluded, perhaps even as a lofty religious and moral personality, or perhaps also as a superman equipped with extraordinary, nay unique, gifts, but withal fundamentally as a man, one of our own time.” (I/2, 64)
The key is “our own time.” The historical Jesus research assumes the basic continuity between the time of Jesus and ours. For Barth, God’s time remains God’s time and our time remain ours. There is a difference of order between these two, and to confuse or collapse them is to deny the apocalyptic or eschatological character of the Gospel. That’s why for Barth, “revelation is not a predicate of history, but history is a predicate of revelation.” (58) The starting point is revelation (God’s time), from which we give meaning to and make sense of history (our time). And not the other way around.