Jesus appears to have taken no steps to embody his teaching about the kingdom in a written form, which would be insulated against distortion by the fallible memories of his disciples. The Christian church possesses nothing comparable to the Qur’an. The teaching of Jesus has come to us in varied versions filtered through the varied remembering and interpretings of different groups of believers. What, on the other hand, did occupy the center of Jesus' concern was the calling and binding to himself of a living community of men and women who would be the witnesses of what he was and did. The new reality that he introduced into history was to be continued through history in the form of a community, not in the form of a book.
It’s easy for Protestants (like me) to balk at what Newbigin says here about Scripture, leading us to then tune out the rest. But I do think he’s making a really important point about Jesus calling “a living community of men and women” to be his witnesses—a community that exists in history and extends across history. Newbigin’s point is that Jesus cared supremely about equipping his disciples (and, by extension, the church) for the task of bearing the presence of God’s kingdom through history. To be sure, Scripture plays an absolutely essential role in that whole process. But there is an unavoidably visible, tangible reality to the church (as the community of Jesus in time) that we can see and point to and trace its development (and declensions) and submit to and so on. This is what, in another context, I referred to (drawing on Richard John Neuhaus) as being an “ecclesial Christian.”