The following diagram has been making its way around the internet lately, and I've got a problem with it. But not for the reasons you think.
First, let's look at what the diagram gets right. It's actually not a bad depiction of how we understand all the source material that went into what we read in the four gospels. Most biblical scholars believe that Mark was composed around the year 70, Luke and Matthew around the year 85, and John later, maybe 90 or later. So these are all gospels that were recorded at least 40 to 60 years after Jesus knocked on doors handing out leaflets in Jerusalem around the year 30 C.E. (CE = Common Era, used to be AD, but that's another story) The purple represents material that is common to three Gospels, the Blue is just common to Luke Matthew, etc. You get the idea. John is off writing his own thing, probably at a Starbuck surrounded by a bunch of Greek philosophy students. The chart communicates, with limitations, the essence of the idea that a) there are different sources for the three synoptic gospels and b) the gospels share a lot, but not everything.
But, here is my problem with this chart. We are losing something in this deconstruction approach to biblical reading. We are losing a sense of story. Yes, it's true that the stories of Jesus were collected, handed down, oral tradition, told and retold, probably edited for the community that originated the narrative. But, that doesn't mean they aren't true. And I don't mean true as in literal newspaper reporting true. I mean deep true. Are the parables of the prodigal son and the good samaritan less vital and vibrant because they only appear in Luke and nowhere else. Does that mean we should discount them as, maybe Jesus didn't actually tell them, or why did only Luke record them? How's that for a run on sentence?
Even if you are a person outside of the Christian faith tradition, or just a healthy skeptic, you still have to appreciate the power of these stories, and the power of the Jesus story. I mean come on people. A man of humble beginnings encounters a radical prophet (John the Baptist) and his alternative community, participates in an initiation rite and heads into the desert for some kind of temptation experience. After being tested in a wild mystical encounter with spirits and angels and demons returns to his homeland and begins teaching a new way of life and living. As he begins healing people and teaching he dislodges the current religious and economic systems and brings his teaching right to the face of the empire that has dominated his people for decades. They respond with brute force, persecution and death. But, he and his message are so significant that the community and the power that initiated the whole movement lives on.
That's a story that needs to be told again and again and again. It's also a story that needs to be lived over and over. You can't diagram that.