How authentic is John's Gospel?

A:There are several dimensions to this question. First of all, the four New Testament gospels were all written anonymously and only attributed to the apostles whose names they now bear, later in the second century. In spite of its attribution, John's Gospel is not authentic in terms of authorship by the named apostle - and biblical scholars say that it could not have been written by an eyewitness to the events portrayed..

The Gospels of Matthew, Mark and Luke are called synoptic gospels, because they are reasonably consistent in their content. John's Gospel differs significantly from the other three. The essentials are there, especially the crucifixion and resurrection of Jesus, but are told very differently than in any of the other New Testament gospels.

The reason for the close similarity among the synoptic gospels is that the Gospels of Matthew and Luke were largely based on Mark's Gospel. When they agree with Mark, they do so with a good deal of consistency, although often with elaborations. Matthew and Luke also contain essentially similar material attributed to the hypothetical 'Q' document. However, it has been demonstrated that John is only loosely based on Luke, with some material taken direct from Mark. The differences are such that it is not possible to say that John is authentic without discounting the synoptic gospels.

The early Church Father Origen, in defending John's Gospel (Commentary on John), said "Although he does not always tell the truth literally, he always tells it spiritually."