The canonical Bible contains four gospels. Three of these, Matthew, Mark and Luke, all focus on Jesus provincial ministry in Galilee and contain many parallels with one another. The common view that they present has led to them being called the Synoptic Gospels (synoptic being Latin for common view). John’s gospel,focuses on Jesus time in Judea and is distinctly different from the other three.

Consider any of the two of the three gospels and they share features not found in the third, thus:

• Mark and Luke exhibit a common order of their material;
• Luke and Matthew share so-called minor agreements;
• Mark and Matthew contain Luke’s omission.

Like the trinity of Father, Son and Holy Spirit, they stand, different yet inseparable. Much of the material within the Sermon forms part of this pool of shared material and is thus found elsewhere in identical or similar form in various parallel passages. In particular, Matthew and Luke frequently contain parallel sermon-sayings not found in Mark, with perhaps as much as half the Sermon potentially falling into the category of minor agreement. Moreover, the Sermon shares only two verses with Mark that are not also found in Luke. The Sermon also contains a number of passages with parallels in the Gospel of Thomas, most of which are paralleled in Luke, but none of which occur in Mark. 

Of Mark’s 660 verses some 600 substantially parallel sections of Matthew, whilst Luke and Matthew share around 200 parallel verses that are not in Mark (Filson 1992, 2:532). In some cases the similarities between the parallel passages are incredibly precise (Tuckett 1996, 3:263), e.g. to the point where they:

• agree verbatim in their Greek rendition of passages that report Jesus’ Aramaic words, as in Matt 7:7-11 and Luke 11:9-13, the Sermon on the Mount’s teaching on God giving  good gifts;
• insert equivalent editorial asides at equivalent points in a narrative, as in Matt 14:3–12 and Mark 6:17–29, where Herod’s reaction to Jesus’ miracles in both cases prompts the back story of John the Baptist’s murder. 

The similarities between the Synoptic Gospels suggest that there is some interdependence between them. However, the exact nature of this has become a source of much debate. This can only be summarised briefly here, but for a fuller introduction see the Synoptic Problem site. 

Theories to account for this have included :

1. all three being dependant upon a common oral tradition;
2. that all are derived from a single earlier document;
3. evangelists using the work of one another.

Some (e.g. Tuckett 1996, 263), see equivalent editorial interventions as powerful evidence against dependence upon oral tradition. Against that, one might argue that it appears to have been traditional within Judaism to memorise Rabbi’s comments together with a contextual narrative. The Talmud, itself the written embodiment of a body of oral material, is full of examples of this. 

Because John’s Gospel is apparently so very different in its portrayal of Jesus’ ministry, the sequence within which events originally unfolded is seen as relatively unimportant in determining any similarities in the synoptic gospel’s ordering of events (Tuckett 1996, ???).

Augustine, proposed the first solution to the synoptic problem, relying on external evidence such as the tradition reported by the Church fathers, that Matthew was the first gospel to be written, he postulated that Mark was derived from Matthew and then Luke from both of them (Tuckett 1996, 6:246).

Eighteenth century Scholars developed a hypothesis (usually attributed to Griesbach), in which Luke borrowed from Matthew and finally Mark borrowed from both (Tuckett 1996, 6:246). The modern equivalent of this tends to be known as the Two-Gospel theory, from the prominence it gives to Matthew and Luke.

Later scholars, working amidst suggestions of very late dates for gospel composition and encouragement to see the world in evolutionary terms, proposed that Mark came first and focussed on the role of oral transmission. From this emerged a two-source theory which sees Matthew’s Gospel as the product of an editor whose foundational inputs were an oral source (Quelle, usually abbreviated to Q) and Mark’s Gospel.

In the latter twentieth century the Two-Source theory enjoyed considerable popularity (Tuckett 1996, 6:246), but as Tuckett’s review of the problem concludes —

‘Many arguments used in the discussion are reversible. Practically all arguments depend on claims to the effect that a development of the tradition in one direction is “more likely” than the reverse development. Clearly, any such claim is subjective, and always potentially open to a counterclaim which tries to account for the opposite change in question.’

(Tuckett 1996, 6:270)

Whilst some have tried to see Q as a formal body of material, such as that documented in the Gospel of Thomas, or the collection of logia made by Papias, the uncertainties surrounding the hypothetical oral ‘gospel’ Q have led others to question its existence. From this latter camp comes the Farrer Theory (Tuckett 1996, 6:246), which has Matthew dependant upon Mark alone and then Luke dependant upon both of them. 

The oral nature of Q, together with the fragmented distribution of parallels within Luke (and the Gospel of Thomas), leads many (e.g Vermes 2004, 372) to conclude that the Sermon is an editorial construct, whose original components came from a wide variety of settings. The two source advocate must therefore attempt to address an important question, which of these sayings are authentically from Jesus? Tom Wright, is convinced that it is inappropriate to consider the Sermon in this way, for, he writes, “Jesus’ redefined kingdom-story, as we are analysing it, creates a perfectly plausible historical context within which Jesus not only could, but, I suggest, would have said things like this” (Wright 2001, 288). Wright therefore suspects the scattered parallel passages, with their local variations, arose through reuse (Wright 2001, 288), of the type that typifies most itinerant preachers. The present author would side with Wright and those who see the Sermon as a single, indivisible, ‘saying.’