There are two great advantages that follow from counting Matthew first.
One is that it follows the independent testimony of history. The other
is parsimony. If Mark goes first, as modern Bible scholars believe, then
an otherwise unknown document known as 'Q' is required to account for the
material Matthew and Luke have in common. William of Ockham's razor requires
us to slash away all unnecessary entities. 'Q' is an unnecessary entity,
since counting Matthew first eliminates the need for it. That doesn't mean
you can't make money selling it, to those suckers willing to shell out
cash for a non-existent book.
The function of the popular conjecture of Mark's priority is to
discredit the other gospels, which, it is alleged, are copied from
him, but with free and unwarranted additions and subtractions:
"In contemporary studies of the way the gospels came
into being, scholars are all but unanimous today in asserting that
Mark was written first and that both Matthew and Luke incorporated
Mark into their narratives. The problem for the excessive claim of a
divine origin for the scriptures then comes when we discover that
both Matthew and Luke changed Mark, expanded Mark and even omitted
portions of Mark. That is not exactly the way one treats something
identified as the 'Word of God,' or even something thought to be
inspired by God." (John Shelby Spong, The Sins of Scripture, p. 22).
Mark is the shortest gospel, so 'expanded' it must be. One can certainly understand why someone like Bishop Spong is attracted
to this conjecture, because his agenda is to discredit the Bible: "I had to
come to the place where I recognized that the Bible itself was often the
enemy." (John Shelby Spong, The Sins of Scripture, p. 11). It is far less
obvious why people who think the Bible is God-breathed also find this
speculative, fact-free construct appealing. Parsimony requires its abandonment.
Writers often provide a clue as to when they are writing. Luke gives, not
a subtle, easily-missed hint, but a giant road-block preventing further
progress. Here is the end of Acts, which continues on from the end of the
Gospel of Luke:
"And Paul dwelt two whole years in his own hired house, and received
all that came in unto him,preaching the kingdom of God, and teaching those
things which concern the Lord Jesus Christ, with all confidence, no man
forbidding him." (Acts 28:30-31).
He leaves Paul in prison, awaiting a hearing and a verdict. Luke drops not so much as a hint of the verdict; to this day people wonder whether Paul was acquitted, and went on to Spain, or whether he was condemned and executed at that time, or whether there was some other outcome. If the verdict had not yet been handed down, this would be understandable; otherwise, not.
"Other explanations, that Acts was left unfinished...are recourses
of desperation. [...] From the internal evidence of the two books we should
therefore conclude...that Acts was completed in 62 or soon after, with
the Gospel of Luke some time earlier." (John A. T. Robinson, 'Redating
the New Testament, pp. 90-92)
Moreover, the Theophilus to whom the work is addressed might be a Roman
prosecutor or other court official. This would explain the very favorable
treatment Acts accords to the Roman authorities. The Roman empire had two
faces. Like the Greeks, the Romans imagined they were civilizing the peoples
they conquered. They were proud of their law, not completely without reason.
But there was another face, a demon face, that peeked out for example when
the Romans conquered Spain, butchering people who had surrendered, butchering
their own allies. This hideous demon face, which Paul, a Roman citizen,
may not have seen in its full horror, was all too evident after 64 A.D.
when Rome burned and the Christians were blamed.
Luke had in front of him a variety of sources when he sat down to compose
"Forasmuch as many have taken in hand to set forth in order a declaration
of those things which are most surely believed among us, even as they delivered
them unto us, which from the beginning were eyewitnesses, and ministers
of the word; it seemed good to me also, having had perfect understanding
of all things from the very first, to write unto thee in order, most excellent
Theophilus, that thou mightest know the certainty of those things, wherein
thou hast been instructed." (Luke 1:1-4).
These already existing gospels must have included Matthew, if not Mark
also. Thus 62 A.D. provides a natural end-point for the composition of
the synoptic gospels.