For interested readers here is a balanced assessment of the historical reliability of the Gospel of John by one of the worlds most respected New Testament scholars. His view is probably shared by the overwhelming majority of specialists in the field.
I think it is important for Muslims (and Christians!) to be aware of what responsible biblical scholars are saying about the gospel of John. This gospel more than any other has laid the christological foundation for later beliefs about Jesus. Yet surprisingly even conservative Christian scholars no longer believe that Jesus actually said the words attributed to him in John.
I think it is important we study these scholars works and learn the reasons why historians have reached their conclusions rather than just cite them as ‘authorities’.
Professor Tuckett writes:
When we turn from the synoptic Gospels [Matthew, Mark and Luke] to the Fourth Gospel [John], we move in some respects into a different world. The differences between John and the synoptics have long been recognised, reference often being made in this context to the famous statement of Clement of Alexandria (early third century) that, whereas the other Gospel writers gave the ‘bodily‘ facts about Jesus, ‘John wrote a spiritual Gospel’ (cited by Eusebius, E.H. 6.14.7.).
Although the differences between John and the synoptics can perhaps be exaggerated, there can be no denying that at many levels John presents a radically different presentation of the life and ministry of Jesus. There are differences at the more superficial level of dates and places, for example in John, Jesus ‘cleanses’ the temple early in his ministry; in the synoptics it is much later. In John, Jesus is active for much longer in Jerusalem; in the synoptics, Jesus is in Jerusalem for only one final week of his life. In John, Jesus dies on the eve of Passover, in the synoptics he dies on the feast of Passover itself. But there are also differences in the whole mode and content of Jesus‘ own teaching: instead of the short pithy sayings and the parables which characterise the synoptic presentation of Jesus’ teaching, John’s Jesus teaches in long discourses with none of the parables so characteristic of the synoptics. So too, categories such as the ‘kingdom of God’, which is so prominent in the synoptics, rarely appear in John; in turn other categories, such as teaching about ‘eternal life’, dominate the picture in John. But the area where this difference is most prominent is precisely the area of Christology.
In general terms, the synoptic Jesus says very little explicitly about himself: his preaching is about God, the kingdom of God, the nature of God’s demands, etc. The Johannine Jesus by contrast is far more explicit about himself so that his teaching focuses on his own person far more directly. John’s Jesus makes himself the object of faith far more explicitly that in the synoptics. John 14:1 is typical: ‘Believe in God, believe also in me’; cf. also 20:31. In the synoptics the motif occurs only in Matthew 18:6 (‘these little ones who believe in me’) which is almost certainly due to Matthew’s redaction (the Markan parallel in Mark 9:42 lacks the phrase ‘who believe in me’). And he teaches quite openly about himself and the importance of his own role on God’s plan, supremely in the great ‘I am…‘ sayings which come throughout the Gospel.
In line with this, the beginning and end of the Gospel focus directly and explicitly on the person of Jesus. Thus the prologue of the Gospel (1:1-18) speaks of Jesus as the Word of God; and in what is probably the ending of at least one version of the Gospel, it is stated that the book has been written ‘so that you may believe that Jesus is the Messiah, the Son of God’ (20:31).
So too the figure of Jesus is portrayed in a more exalted role throughout the story. Jesus is fully in control of all the events concerned. His miracles highlight his person, and indeed at times Jesus acts in order to highlight even more his activity. Thus in chapter 11, when Lazarus falls ill and dies, Jesus is portrayed as deliberately delaying going to heal him in order apparently to make the miracle of raising him all the more stupendous (11:4, 15). John describes what appears to be a vestige of the agony scene in Gethsemane (12:37); but in John there seems to be no real agony on Jesus’ part and Jesus displays unbounded and unquestioning confidence in God. So too, in the account of Jesus‘ actual death, little if anything is made of Jesus‘ suffering. Jesus admits to thirst on the cross, but only in order to fulfil scripture (19:28); and his final word is no agonized cry of dereliction, as in Mark, but a statement of supreme confidence: ‘it is finished‘ (19:30). Above all, it is John that we get the two most explicit statements in the New Testament about the divinity of Jesus. Moreover they come at key points in the narrative – at the beginning and at the end – encompassing the whole story in a powerful inclusio. Thus the first verse of the prologue affirms that the Word was not only in the beginning ‘with God’, but in some sense also ‘was God‘ (1:1); and Thomas at the end of the story openly confesses Jesus as ‘my Lord and my God’ (20:28). John thus presents Jesus explicitly in far more exalted terms than anything we find in the synoptic Gospels.
In terms simply of historical reliability or ‘authenticity’, it seems impossible to maintain that both John and the synoptics can be presenting us with equally ‘authentic’ accounts of Jesus‘ own life. (By ‘authentic’ accounts I mean here historically accurate representations of what Jesus himself actually said and did. The theological ‘authenticity’ of John’s account is quite another matter). The differences between the two are too deep seated and wide ranging for such a position to be sustainable. If there is a choice, it is almost certainly to be made in favour of the synoptic picture, at least in broadly general terms. The Johannine picture then presents us with a view of the Jesus tradition which has been heavily coloured and influenced by John and his own situation.
Extract from Christopher Tuckett, Christology and the New Testament pp.151-152, in chapter 9: ‘The Gospel of John’.