To write the theology of John is a daunting and almost presumptuous undertaking. The evangelist has already written his theology in narrative form. Who are we to rewrite it for him? Moreover, Rudolf Bultmann masterfully set forth the theology of the Gospel and Epistles of John in slightly less than a hundred pages of his Theology of the New Testament, Why should we now need more than half that much space again?

The mere fact that John wrote a narrative of Jesus' ministry means that we should ask whether that historic ministry provides the proper, or complete, context or frame for interpreting what he has written. Apart from that ministry his narrative is unthinkable, but, as J. Louis Martyn argued in History and Theology in the Fourth Gospel, the narrative operates at two levels, that of Jesus himself and that of the Johannine Christians and community. To elucidate John's theology means not to destroy his narrative, but to show how its theological emphases arose from and relate to the emergence of that Christian community on Martyn's second level.

The length of the book is partly the consequence of its intended audience and pedagogical purpose, but mainly a reflection of our increased knowledge. As John Ashton (Understanding the Fourth Gospel) has pointed out, Bultmann did not deal adequately with the question of the historical setting of the Fourth Gospel, particularly as it impinges upon its theology.