Barth does indeed say that the object of theology is "the Word of God in Christ", but on closer analysis this Word is a far broader concept than the person of Jesus. It would seem to be Jesus as the fulfilment of the covenant. On p. 23 Barth defines the phrase "the Word of God in Christ" as “God's Word spoken both in the relation of the history of Israel to the history of Jesus Christ and the relation of the history of Jesus Christ to the history of Israel". The Jesus of the gospels would seem to be one instantiation of this Word in Christ, which can only be fully comprehended in the context of a two-testamental witness, neither of which is subordinated to the other.
Am I reading Barth right here? Is God's covenant with humanity the heart of the Gospel and Scripture?
. . .Regardless of whether 'covenant' is the correct term to describe the Gospel's centre, the idea that "the Word of God in Christ" is the object of theological study, rather than the concrete Jesus as presented in the gospels narratives, finds an echo in something Seitz wrote in his article "In Accordance with the Scriptures" (1996). The context of discussion is the theological significance of the fourfold gospel witness:
"It is not that Jesus is hidden behind the words about him, which must be sifted and probed to get at "historical Jesus". it is rather, that the words that tell about him simultaneously convey their inadequacy, in formal terms, because of the subject matter that they are trying to reach. The very fourfoldness of the gospel record is a witness to the majestic difficulty of the endeavor of presenting jesus as a character of time and space, fully man, fully God. But this is not an inadequacy that can be remedied through historical-critical heavy lifting, because it inheres with the subject matter itself, which is God in Christ - who exposes our inadequacy in trying to speak of him, and yet simultaneously remedies this through the work of the Holy Spirit in the church, allowing the frail testimony of human minds to be the lens on the glory of God, a touching of the ark of the covenant." (p. 58).