I am reading through what is so far an extremely interesting book in the Ashgate “Barth Studies” Series entitled, Karl Barth and the Fifth Gospel: Barth’s Theological Exegesis of Isaiah (by Mark S. Gignilliat). (I will be reviewing it for International Journal of Systematic Theology.) I’m only just beginning it, but already Gignilliat alerted me to this wonderful little passage in vol I.2 of the Barth’s Church Dogmatics where Barth speaks formally about his view of the importance of the Old Testament as part of the Christian canon:
Neither in the New Testament nor in the documents of the 2nd-century post-apostolic period do we find the slightest trace of anyone seriously and responsibly trying to replace the Holy Scriptures of Israel by other traditions of other nations, all those nations within which the first Churches sprang up, or to proclaim those traditions as prophecies of Christ and therefore as a more suitable introduction to the New Testament Bible. Yet this would have meant a great easing of the missionary task, and apologetics often tended in this direction, although hardly ever with reference to the problem of the Canon. Even Marcion never plunged in this direction, although he was near enough to it. We cannot plunge in this direction, we cannot even try to do what Marcion and after him the Socinians and Schleiermacher and Ritschl and Harnack tried to do, without substituting another foundation for the foundation on which the Christian Church is built. The Old Testament is not an introduction to the real New Testament Bible, which we can dispense with or replace. We cannot eliminate the Old Testament or substitute for it the records of the early religious history of other peoples, as R. Wilhelm has suggested in the case of China, B. Gutmann in some sense in that of Africa, and many recent fools in the case of Germany. If we do, we are not merely opposing a questionable accessory, but the very institution and existence of the Christian Church. We are founding a new Church, which is not a Christian Church. . . . Whether we like it or not, the Christ of the New Testament is the Christ of the Old Testament, the Christ of Israel. The man who will not accept this merely shows that in fact he has already substituted another Christ for the Christ of the New Testament. It was not to dissolve the Law and the prophets but to fulfil them that the real Christ of the New Testament came (Mt. 5:17; cf. Jn. 10:35).