It is something of an interesting fad, but the thought of Karl Barth is receiving signficant attention of late from American intellectual historians, who are raising his influence to considerable proportions outside the theological realm.
Perhaps the most popular level example of this, comes from Mark Lilla's new book on political theology, "The Stillborn God". In it Lilla bestows upon Barth so much signficance as to actually implicate him in paving the way to the rise of Hitler.
This sound surprising, since Barth was the main figure behind the Barmen Declaration. The arguement basically suggests that Barth's crisis theology depicted such a sundered world with its "wholly other" conception of God that it constituted Gnosticism. The idea here is that Barth lapses into Gnosticism sense his conception of God could not make anything in history redemptive or of value. This leads to a messianic hope for redemption, which paved the way to Hitler.
It probably is the most criticized part of Lilla's book since he provides no real argument for it. He also forgets to state that it is an interpretation significantly influenced by the likes of Hans Jonas, Hans Blumenberg, and Eric Voegelin (in one way or another). My criticism of it is more of a question. Specifically I wonder how big the readership of The Epistle to the Romans was and how quickly its ideas were able to trickle down into a mainstream Protestant audience. Here again, Lilla can be criticized since he ignores Catholics in his book and almost gives the impression that German Catholics bought up Barth's theology during this short time.
A second work of intellectual history in which Barth plays a significant role is Samuel Moyn's, "Origins of the Other, Emmanuel Levinas. between Revelation and Ethics". In it he basically argues that Levinas's conception of the other is basically a secularized theological version of alterity, which was heavily influenced by Karl Barth. Very fascinating reading.
Moyn has just written another article entitled, " From experience to law: Leo Strauss and the Weimar crisis of the philosophy of religion" in which he argues that the development of the political philosophy of Strauss must be seen in light of the theological upheaval that Barth's theology caused in Germany.
Lastly, I have not read it, but the intellectual historian Benjamin Lazier has just written a piece entitled: "Pauline Theology in the Weimar Republic: Hans Jonas, Karl Barth, Martin Heidegger,” in Hava Tirosh-Samuelson and Christian Wiese, eds., Judaism and the Phenomenon of Life: the Legacy of Hans Jonas"
What is to be made of all this? Let me suggests that as intellectual historians have turned their gaze on major philosophical and political figures, such as Levinas and Strauss, it has become imperative to read theology. Let me put it differently: The philosopher, especially those interested in the so called phenomenological turn to theology, from a certain vantage point do not have to concern themselves with the origins of the other or alterity. It is the historians duty to discover this very thing and it inevitably leads to theological sources. What does this mean? Some would say it means very little and others would call the legitmacy of, say, something like the atheistic turn to alterity in question. There is an important question though and that is to what extent must philosophy rely on a residually theological discourse. There are a lot of options here, but at the very least I do not think it is a trival question.