Part of Bultmann’s work involved elucidating this dynamic in the New Testament, and this comes down to a question of how it came to be that attention in the earliest Christian communities shifted from the message that Jesus proclaimed to a sense that Jesus himself was the message that needed proclaiming. Bultmann’s way of navigating that issue is central to his development of what we might clumsily call his existential christology. The following material helps to get at that issue.
Konrad Hammann, Rudolf Bultmann, 180–82. Bold is mine.
Bultmann asserts the inner connection between christology and Paul’s teaching on justification. As a form of direct address, christology is the proclamation of the eschatological deed of God that occurred in Jesus Christ, while as a form of indirect speech, christology makes explicit the new self-understanding of the believer that is made possible through the salvation-event. Thus, justification proves to be the explication of christology, just as talk of Christ is conversely understood as implied by the event of justification. Since Paul emphatically unfolds christology after the manner of a doctrine of justification, he makes clear that an understanding appropriation of the Christ-occurrence “is a matter not of speculation, but rather of self-reflection, a thinking-through of one’s new experience.”
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In essence . . . the proclamation of Jesus has no significance for the theological views of Paul. The evident similarities and differences between the preaching of Jesus and the theology of Paul with regard to the law and eschatology cannot be explained in terms of the history of ideas—that is, as if one had developed out of the other. Rather, the decisive difference consists in the fact that “Paul regards as present what for Jesus is future—which is to say, as something in the past breaking into the present.” Bultmann now views two stages as significant for the emergence of christology. Jesus understood himself as bearer of the word of God in the end times. His call to decision in the face of his person implied a christology. Thereupon, with its confession of the crucified Jesus as the Messiah, the earliest community understood the cross as the eschatological deed of God and understood itself anew on this basis. What was implicit in the kerygma of the earliest community, Paul made explicit in his theologia crucis, namely, the meaning of the cross as the decisive fact of salvation for the self-understanding of the believer. But since Jesus Christ encounters a person solely in the proclaimed word, one may “not go back behind the kerygma . . . in order to reconstruct a ‘historical Jesus.’” . . . In his theology, therefore, Paul interprets the new self-understanding of those who believe in the Christ present in the kerygma as Lord over their existence.