(From Dave Black Online. Used by permission. David Alan Black is author of Energion titles The Jesus Paradigm, Christian Archy, and Why Four Gospels?.)
9:55 AM Why the Gospel of Luke?
Through hindsight we can determine the assignment that Luke received from Paul by comparing the Gospels of Luke and Matthew and by noting Luke’s deviations. In the first place, Luke carefully followed the main structure of Matthew throughout and generally adhered to the order of its various sections and anecdotes, though he also made highly interesting changes. For example, his story of the birth of Jesus is totally different from Matthew’s, which (as we have noted) was almost entirely apologetic in tone and content. Luke, however, provided a straightforward narrative that stems either directly or indirectly from Mary herself. When Luke came to Jesus’ Galilean ministry he added certain details to each of the stories from Matthew’s Gospel that he decided to adopt. Indeed, in one way or another he absorbed nearly everything that Matthew had written, and yet managed to add a good deal of extra material. Luke did this by omitting a number of duplicate stories (e.g., the famous Lukan omission of Matt. 14:22–16:12) and by inserting into the heart of the Matthean text at the end of the Galilean ministry (cf. Matt. 19:1–2) a section of no less than nine long chapters, Luke’s central section (9:51–18:14), comprising (1) the excerpts that he had extracted from Matthew’s five great discourses in order to lighten the content of his own version of them and (2) additional sayings and parables that Luke had collected. (It is perhaps worth noting here that Luke’s central section roughly corresponds to the conjectural document known as Q, which many modern scholars consider to be one of the sources of Matthew and Luke.)
From Why Four Gospels?