As any educator can testify to, when the work of two students is so similar (often verbatim), we naturally suspect copying is going on. More often than not, one student copies the work of another and so it then becomes our task to investigate and pinpoint the origins. Less often the case is that both students shared the same source and copied the same section out verbatim. It’s less likely for obvious reasons, what are the chances two students working independently from one another managed to stumble across the same source and then copied the same sections of that source? But it is precisely this, that many scholars think, has happened with Matthew and Luke. The material shared between Matthew and Luke (DT material) that is not found in Mark share the same phenomenon that the TT material has. This double tradition material is almost word-for-word agreement. Here we will investigate the evidence for the solution scholars propose to explain why many of the stories Matthew and Luke share (that are not found in Mark) are so close in wording.
The long accepted answer to this comes from over 100 years ago, properly formulated by BH Streeter, and that is the hypothetical document you may have heard of referred to as “Q.” “Q” comes from the German Quelle meaning “source.” Streeter’s formulation, that is still widely accepted today, is that almost all of Q’s contents can be found in Matthew and Luke. It was written in Greek and so is not the result of oral tradition (since Jesus would have spoken Aramaic), and that Luke more often than not preserves the original order of the logia (logia is just a collection of sayings belonging to Jesus) while Matthew tinkers and fiddles with its order. And this completes the two source theory: that Mark and another document (Q) are sources for Matthew and Luke.
The interesting thing about Q is that we don’t actually have any archaeological find which can be a witness to Q. In the sense that we have Q preserved in Matthew and Luke but without access to an original the job of the redaction critic is made much more difficult. We do have documents from antiquity, like the Gospel of Thomas, that resemble what many believe Q would have looked like as it is hardly any narrative, it is mostly Jesus sayings. The Gospel of Thomas dates back to anywhere between 60 and 140 CE—though since Robert E. Van Voorst’s analysis most scholars accept it is a 2nd century document that preserves earlier 1st century oral traditions—the point is though, Q would set a precedence for this type of literature—a sayings gospel. It is worth pointing out some of the narrative in Q—we have speeches from John the Baptist, the story of the Centurion’s boy and the Temptation of Jesus as examples of some more famous ones.
So why do scholars introduce an extra unknown? If Matthew and Luke used Mark as a source but are independent of one another, and most scholars think they are, it then follows that they must have had another source they both worked from independently of one another. Thus Q. So the question is, why do we think Matthew and Luke are independent of one another? What will follow is a positive case for Q. In the next part we will return to the case against Q. But for now, this is where the case for Q really kicks in.
Argument from Order
Q scholars typically argue that if Luke had known Matthew’s Gospel, it is very unlikely he would have destroyed Matthew’s order, i.e. the chronology of the events in Matthew. The most frequently used example demonstrating this is the Sermon on the Mount in Matthew chapters 5 to 7. The Sermon on the Mount has throughout history been heralded as one of the finest pieces of religious literature ever produced and today we are in a rather lucky position as we can see just how talented, through all our forms of literary criticisms, and just how beautifully written this piece of text out of antiquity is. Luke takes 30-odd verses from the sermon as one chunk and redistributes the rest of the sermon in later stories in his gospel. Q scholars argue this type of thing is thought to be rather implausible so Matthew can’t have known Luke’s Gospel! Instead it is thought they worked from another source, i.e. Q, and distributed the Jesus sayings in Q in different parts of their Gospels. So if it seems implausible to you that Luke would tear apart such a wonderfully written sermon, then surely Q makes better sense of the data.
Argument from Redaction
Simply put, Luke seems to lack a lot of the Matthean redactions of Mark. In other words, if Luke was using Matthew as a source then surely we would see some of the little edits in Luke that Matthew makes to Mark. And Q scholars argue against there being any. They also argue against Matthean expansions popping up in Luke so if Luke is copying out of Matthew, it’s strange that he doesn’t seem to have any knowledge of the Matthean expansions of those same stories. Which you would expect to see if Luke is copying from Matthew. So Q scholars suggest that since we don’t find that, it must be that Luke doesn’t know Matthew and it begins to be likely that he knew Mark and Matthew’s source, but not Matthew. For example, in the story in which Jesus walks on water, Matthew has Peter following Jesus out on the water too; this little bit is missing from Luke’s account of Jesus walking on water. If Luke was copying from Matthew there doesn’t appear to be any reason why he would leave this bit of information out. In the story of Jesus’ commendation of Peter at Caesarea Philippi; when Jesus asks Peter who people say he is Peter says “Some say John the Baptist, but others Elijah, and still others Jeremiah or one of the prophets.” Responding to this Jesus asks, “who do you say that I am” and Peter replies, “you are the Messiah, the Son of the living God” and Matthew includes a reply from Jesus not found in Luke:
“Blessed are you, Simon son of Jonah! For flesh and blood has not revealed this to you, but my Father in heaven. And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hades will not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven.”
This is the establishment of the church! If Luke knows Matthew’s Gospel then why wouldn’t he include this?!
There are also bits of special M (material that is only found in Matthew) that would appear to assist and help Luke’s cause so it’s rather strange this material isn’t included had Luke known Matthew. For example the significance of the Magi in Matthew chapter 2 would fit in nicely with the pro-Gentile motifs found in Luke. Luke is commonly referred to as the Gospel for the Gentiles, it’s very pro Gentile and there at the beginning of Matthew there are these gentiles who come and worship Jesus. So it would seem an odd thing to leave out of Jesus’ birth narrative if Luke had access to Matthew. But keep this story in mind because we will return to it shortly.
In my opinion the argument from “alternating primitivity” is the strongest argument for Q. Put simply this is all about sometimes-Matthew and sometimes-Luke appearing to have a more primitive form of a given saying. So if one author were working from the other, what we might expect to see is that only one Gospel, either Matthew or Luke whichever came first, has a less embellished, less elaborated version of a Jesus saying. What we see in both Gospels however, and this is closely related to the criterion of embellishment (a historical criterion we will return to in another post), which we see in many writings of antiquity where younger versions of a story have had extra details added on or certain aspects of the story embellished indicating that generally stories are elaborated in the re-telling. What we see in Matthew and Luke are what appear to be forms of a Jesus saying which swap primitivity between the two gospels. So in other words, Matthew or Luke pick the same Q saying yet only one of them will embellish the saying. An example is best to make sense of this. Let’s draw our attention to the first “Blessed are the poor in spirit, theirs is the kingdom of God,” this is a beatitude, that is any saying where Jesus declares blessedness, and we find them in the Sermon on the Mount. So Matthew chapter 5 we read, “blessed are the poor in spirit” contrasted with Luke 6 which reads “blessed are you who are poor, for yours is the kingdom of God.” Q scholars point out that the passage in Luke, “blessed are the poor”, must have been the original Q version and Matthew secondarily spiritualizes it. It is easier to imagine that during Matthew’s redaction he adds on a Christology which we know developed during the first century, as opposed to Luke leaving it out. The Lord’s prayer is a common second example that shows Matthew spiritualizing a Q saying. The version I read out in school at the end of every day, is found in Matthew and it reads “Our farther who art in heaven, hallowed be thy name” whereas the Luke version found in chapter 11 we read, “father, hallowed be thy name.” This is a common thing for Matthew to do, he often adds things like “who is in heaven” to his writing. Luke looks primitive and Matthew looks secondary, so Luke likely has the saying which either closely resembles or is found in Q. An interesting phenomenon we see among the manuscript tradition are where scribes are copying out Luke Gospel and when they get to the Lord’s prayer, the begin copying out Matthew’s version of the prayer! Clearly Matthew’s version permeated Christian communities a whole lot better than Luke’s version and scholars commonly explain that Matthew’s more spiritualized version resonated with early Christian communities a whole lot better. So because of this alternating primitivity Q must have been the source to Matthew and Luke.
This is however not the end of the story. In Part II we will discuss some of the weaknesses with the hypothetical sayings source, Q.
 See Dale C. Allison, The Structure of the Sermon on the Mount, JBL, 106/3 (1987) 423—445