John's Gospel includes a broad spectrum of witnesses to Jesus, whose wide-ranging responses and stories are an attempt to persuade audiences of their points of view on Jesus, which range from positive to negative. The evangelist wants his readers to become more confident in their faith, hence his desire to tell a credible story (or series of stories) about Jesus.

Credible Witnesses follows John's lead by allowing many of his characters to speak about Jesus by telling their stories. This involves imagination and even conjecture at times. In each of the chapters of this book, a character's testimony is illuminated with some background information, before going on to show how John uses the testimony as part of the witness of his Gospel as a whole. Each chapter ends with some reflections that help to draw John's Gospel into the present.