The Gospel of Mark is the only independent account of the life and death of Jesus. The other three, Matthew, Luke, and John are all derivatives of Mark. And they each consciously and purposefully changed Mark’s narrative to suit their own particular non-historical needs.

Take for example Jesus’ last words on the cross:

Mark, which was originally written in Greek, shifts to Aramaic when “quoting” the last words of Jesus, transliterated into Greek characters: Eloi eloi lama sabachthanei (My God, my God, why hast thou forsaken me? – Mark 15:34). He then writes that some bystanders misheard and assumed that “he is calling Elijah [Eleian]” (Mark 15:35). This “quotation,” of course, comes directly from the opening verse of Psalm 22. Matthew, writing a new gospel based on Mark later, knew that Mark’s Jesus was quoting Psalm 22:1 as his last words on the cross. However, he had a problem with the logic of Mark’s bystanders who mistake Eloi for Eleian – the two words simply do not sound very similar. So, instead he transliterates the Hebrew of Psalm 22:1 into Greek letters: Eli, Eli, lema sabachthani? where Eli can be more easily confused with Eleian. Of course, Jesus spoke Aramaic, not Hebrew, so Matthew’s account of Jesus’ last words is clearly a fiction but one that Matthew felt justified in doing, apparently because it better preserves the literary connection with the Psalm and better explains the bystander’s mistake.

Luke plays even more fast and loose with Mark’s text. He knew perfectly well how Mark recorded Jesus’ last words but clearly did not consider this a “historical fact” not open to changing – because that is exactly what he did. Luke completely drops the quotation from Psalm 22:1 and the bit about the bystanders mistaking what they heard and replaces it with something entirely different: “Then Jesus, crying with a loud voice, said, ‘Father, into your hands I commend my spirit.’” (Luke 23:46). Luke borrowed this quotation from a different Psalm, this time Psalm 31:5. In the process of doing so, Luke implicitly declares that Mark’s account is a fiction and self-consciously presents his own account as a fiction. Such methods are not done for historical purposes but for literary purposes – each author has a religious message that he or she wishes to convey and the details of the story are not as important (and thus can be easily changed) as the theological conclusion. John works the same way, rejecting both Mark and Luke and making Jesus’ last words to be simply “It is finished.”

You can take, as another example, how the gospels frame the revelation of the empty tomb:

In Mark’s narrative, the three women approach the tomb wondering how in the world they will be able to roll the stone away, but when they arrive they find that the stone has already been rolled away. There inside the tomb is the young man, and the implication is that the young man rolled the stone away so that the resurrected Jesus could walk out. In other words, Mark believed that the risen Jesus was a resuscitated corpse, and that Jesus required the stone to be rolled away so that he could exit the tomb. The young man declares that Jesus has already left, and that he is now on his way “ahead of you to Galilee.”

Matthew, however, I would argue did not agree with Mark’s resurrection theology, so he deliberately changed the story. In Matthew, the women arrive and find that the tomb is still sealed – the stone is still covering the entrance. Then they watch as the angel rolls the stone away to reveal an already empty tomb. In other words, Jesus has already risen and passed straight through the stone as if he was some sort of phantasm. The risen Jesus was not a resuscitated corpse, but a spiritual body who could later appear as an apparition to his followers. Again, Matthew implicitly declares Mark’s account a fiction and self-consciously presents his own fiction to replace it. This is not an example of two eyewitnesses reporting different details of the same event. Matthew’s changes have important literary and theological consequences for the narrative.

Whereas Matthew altered Mark’s account so that the tomb is still sealed when the women arrive (and thereby setting up his dramatic reveal of the empty tomb by the angel), Luke follows Mark by having the stone already rolled away from the tomb. Luke also gets rid of Mark’s mysterious “young man” and instead replaces him with something more fantastic – not one, by two men and not dressed in a plain old “white robe” but in “dazzling clothes” and speaking as one voice! Had Mark known about these spectacular new details, then he would have surely written as much. However, Luke’s most dramatic change is the way that he completely re-writes the “angel’s” message from what the young man says in Mark. Rather than “he is going ahead of you to Galilee,” in Luke the angels say, “Remember how he told you, while he was still in Galilee, that the Son of Man must be handed over to sinners, and be crucified, and on the third day rise again.” Whereas Matthew followed Mark’s cue and presented the post-resurrection appearances in Galilee that Mark only hints at, Luke has something entirely different on his mind. Instead, he plans on restricting the resurrection appearances to Jerusalem so that he can prepare his readers for the story of Pentecost in the book of Acts (widely believed to have been written by Luke as well). Therefore, he cannot have the angels tell the women to go to Galilee (some 80 or 90 miles north), so he leaves “Galilee” in the speech but changes the meaning of it completely. Luke then follows this by presenting only resurrection appearances in the vicinity of Jerusalem. Here the literary, rather than historical, nature of what Luke is doing is most explicit.

John is even more different, and seems to pull in elements from both Matthew and Luke to create what is essentially a more complex narrative.

Matthew, Luke, and John, did not treat Mark as a historical document, let alone an eyewitness account, but as a literary narrative, the details of which were freely open to change depending on the religious message that the author wished to convey. If Matthew, Luke, and John did not treat Mark as a historical document, filled with inalterable factual details, then why should we?