So what basis is there for seeing unity in the midst of such diversity? I suggest the following five foundations, offered in approximate order of significance in my mind.
- The various NT authors explicitly or implicitly work from the same basic kerygma. A comparison of the Gospels with the speeches in Acts as well as the teaching in the epistles reveals a basic sequence of events and actions pertaining to Christ that unify their message and establish parameters for true in contrast to false doctrine. Especially helpful in this regard is the work of C.H. Dodd, The Apostolic Preaching and its Development.
- The various NT authors all wrote in the context of the mission of Jesus and the extension of that mission through the church. Each of the NT documents arose in the context of missionary expansion of the church. The Gospels testify to the mission of Jesus, Acts connects the mission of the church to the mission of Jesus, the Epistles address issues arising in the advance of mission, and Revelation describes the consummation of Jesus' mission in a new heaven and new earth. Particularly noteworthy on this point is the work of David Wenham, "Unity and Diversity in the NT," in G.E. Ladd, A Theology of the NT, 712-713.
- The various NT authors all claim continuity with and fulfillment of the OT hope. Although done in a variety of ways (promise/fulfillment, typology, salvation-history), all of the NT authors see the person and work of Jesus as the realization of what the OT promised. Note here should be made of C.H. Dodd, According to the Scriptures: The Sub-structure of NT Theology. THe OT supplies the conceptual framework for their understanding of Jesus and significance of his actions.
- The divine inspiration of the various NT authors produces a demonstrable unity of thought. I have placed this one fourth for the simple reason that I want to show that arguing for unity in the NT does not exclusively hinge on accepting the inspiration of the NT. Of course, as one who firmly believes in the inspiration of both the OT and NT, it makes sense that there would be unity in the various documents if He was in fact responsible for their production. In one sense then we could argue that the diversity of the NT documents is a product of the individual human authors and their peculiar modes of thought/expression, while their unity is the result of the one Spirit inspiring those different authors to produce exactly what God wants said exactly how he wants it said.
- The recognition by the church of these NT documents as inspired and authoritative led them to organize them into the canon. The very fact that the church recognized some documents as authoritative and others as not demonstrates a conviction that there is in fact a core to the apostolic message. While not denying that this was a process not without dispute, the church's recognition of these documents indicates a perceived unity among the 27 documents that should not be dismissed lightly.