It is true that Paul did not speak as much about the earthly life and ministry of Jesus as we would have liked. Rudolf Bultmann claimed, “The historical Jesus plays no role or practically none in Paul.” Such conclusions have led some to see Paul as inventing a Christianity different from that of Jesus. That is surely an exaggeration but how are we to understand how Paul speaks of Jesus?
Ben Witherington III, in his book Paul’s Narrative Thought World, gives a helpful response to Bultmann’s concerns.
Bultmann’s influential criticism is mitigated, if not vitiated, in five ways:
(1) by considering where in the story of salvation history Paul locates himself and Jesus;
(2) by recognizing that they shared a common eschatological outlook;
(3) by noting that Paul’s letters are addressed to those who are already Christians, and thus they likely do not contain much material that Paul would have preached to these people were not yet Christians;
(4) by recognizing that in fact Paul does at various points rely on the Jesus material, both quoting from and alluding to it;
(5) by recognizing that there is a profound agreement between the essence of Paul’s theology, even the theology he received by revelation, and various parts of the Jesus material especially the parables. (pp. 147-48)
If you are interested in more about Paul and Jesus, read my article that was published in the McMaster Journal of Theology and Ministry.