I have said all this before, and have shown how Karl Barth has taught me these moves. And I've tried to show some of the significance of this connection between resurrection and trinity. Let me indicate a further point of significance I just stumbled on this week. In his discussion of the event of vocation (CD IV/3, §71.2), Barth asks, who is the acting subject of vocation? Who calls humans to the service of witness? In the course of his answer, Barth draws on the trinitarian grammar of Easter:
If, in those passages which speak more generally of calling, God as well as Jesus Christ is described as the One who calls, this is not, of course, an indication that the New Testament knows two kinds of vocation, the one effected by God the Father, the other by Jesus Christ, and possibly a third by the Holy Spirit. It rather corresponds to, and is even interconnected with, the fact that in the New Testament there are also two ways of speak of the Easter event: on the one side, it is Christ's raising up by God the Father, and on the other it is his own resurrection, and a third possibility may perhaps be seen in Rom. 1:4 with its reference to the power of the Holy Spirit operative in this event. In both cases the statements are complementary. To the question of the concrete form in which God calls, the only answer is obviously that it is Jesus who does it in all the concreteness of his humanity. And to the question of how he does it, the only answer is obviously that in what this man does God is at work in his eternal mercy and omnipotence. The New Testament does not see two or three things here, but only one thing. (CD IV/3, p. 503, rev.; KD IV/3, p. 579)So Barth argues for the living activity of Jesus Christ in the calling of humanity by reference to the triunity of God in the Easter event. Just as God in Christ is the subject of resurrection, so God in Christ is the subject of vocation. This point becomes crucial for Barth in securing the content of the doctrine of vocation Christologically: namely, that the the goal of vocation is sonship, fellowship, and union with Christ (§72.3), and that the concrete form of vocation is the service of witness to him for the sake of the world (§72.4).