This is another of those examples that shows us that the evangelists – Matthew, Mark, Luke, and John – were not as concerned with reporting the details of an incident as they were with expressing the meaning of the experience. It’s similar to the question of “when did Jesus rise from the dead?” Was it “when the sun had risen” (Mark’s Gospel) or “while it was still dark” (John’s Gospel)?
It’s good to pay attention to such discrepancies because they often alert us to a point that the evangelist is making. In both cases (the Crucifixion and Resurrection), it would seem that John’s Gospel manipulates chronology to make a significant theological point. In the case of the Resurrection, John uses the image of light and darkness throughout his Gospel, beginning with his Prologue in chapter 1 and culminating in Jesus declaring himself as the “light of the world” (8:12) It makes sense, then, for John to emphasize Jesus’ followers coming to the tomb “while it was still dark” in order to once again reinforce the notion of Jesus as the light of the world for a people who walk in darkness. In a similar way, John’s Gospel places a lot of emphasis on the Passover and it would seem that he manipulated the chronology of events concerning the Passover in order to stress a theological point.
In John’s Gospel, Jesus visits Jerusalem 3 times: in chapters 2, 5 and 12. Each visit coincides with the celebration of the Passover. In the final visit, Jesus himself becomes the Passover sacrifice as he is crucified on the day in which the Passover lamb is to be slaughtered. Is John deceiving us by manipulating the chronology of events? Not at all, since his concern was not to record a historical narrative of events or a chronological biography of Jesus but rather was interested in conveying the meaning of the events of the death and Resurrection of Jesus. In this way, the Gospels can be thought of as being more like portraits than photographs: in a portrait, the artist puts a little bit of him/herself into the finished product.