The Gospel of John presents a distinct picture of the life and ministry of Jesus. Whereas the Synoptics relate Jesus’ aphorisms delivered before the simple crowds in the rustic backcountry of Galilee, John’s Gospel attributes to Jesus lengthier theological discourses and elevated claims to God-like status (e.g. the “I am” statements).
Other differences include:
The emphasis throughout the Gospel on Jesus’ ministry in and around Jerusalem and his interaction with the ruling classes of the city.
The recording of disputes with the Pharisees that seems to presuppose an understanding of proto-rabbinic theological concerns.
Transcripts of the deliberations of the high priest and the Sanhedrin.
Origen long ago sought to account for the differences between the Gospel of John and the Synoptics by arguing that the Gospel of John was not a historical account of Jesus’ ministry, but was rather a “spiritual” gospel whose narratives were allegorical in nature. Many contemporary evangelical leaders, such as Craig A. Evans and Michael Licona, have claimed similarly.
There is, in my view, a better explanation, and it is that the author of John’s Gospel was an educated Jerusalemite (e.g. Polycrates’ claim that John was a priest and Jerome’s claim that he was born to nobility) who was uniquely placed to understand the significance of Jesus’ theological discourses, and subsequently to pass them down to posterity.
This has been obscured by the tradition, dating to around the turn of the third century, that John’s Gospel was written, not by an educated, priestly Jerusalemite, but by a semi-literate Galilean fisherman. Indeed, it was the unlikelihood that a fisherman could have written the fourth Gospel, coupled with its elevated theology and hints of Philo, that suggested to scholarship in the eighteenth and nineteenth centuries that the work had been composed by Gnostics in the second century.
Such a view has now largely been laid to rest, as it has become apparent that the Gospel of John is very much a product of pre-AD 70 Palestine. Archaeology has confirmed that the author knew Jerusalem before its destruction, and the work also demonstrates familiarity with the theological currents of the time, as has been especially demonstrated by the discovery of the Dead Sea Scrolls.
Why is John’s Gospel so different from the Synoptics? Because, I would suggest, its author had the theological framework within which to understand Jesus at a level lacking to the Galilean disciples, enabling him to write his own unique portrayal of Jesus’ ministry. Anyone reading the Gospel cannot be struck at how the disciple whom Jesus loved understood his master when his closest disciples, the twelve, were often oblivious to his meaning. It is this that imparts to John’s Gospel its distinctive perspective, lacking to the Synoptics.
Furthermore, as an aristocratic Jerusalem himself, who was known to the high priest and to his palace, he would have been positioned to witness Jesus’s interactions with the Jerusalem elite (e.g. Nicodemus) in a way perhaps lacking to the others.
It was this social standing and theological framework which enabled John to record his unique account of the ministry of Jesus.