The first question was why there was so much similarity between Matthew and Mark and Luke. Though there is no consensus, the majority opinion of scholars is that Matthew and Luke used Mark as their source for many of the narratives contained in the their gospels. (Small narratives contained in a larger story are called pericopae, meaning a set of verses that form a unit or, in other words, a chunk.)That made sense for several reasons.
- Mark is grammatically and syntactically rougher than either Matthew or Luke. This can be seen in the English translations, where many of Mark's transitions are made with the simple word "immediately," but is even more obvious in the Greek text. It is supposed that the latter writers improved the literary quality of Mark as they borrowed from it. The opposite - Mark's use of Matthew, for example, but making the story rougher - seems unlikely.
- And many of the pericopae found in Mark and in one or both of the other gospels are shorter in Mark. In other words, Matthew and Luke tend to add information to what is supposed by many scholars to be the original source. Their conclusion that Mark is the first rests upon the text critical principle that the shorter version is more likely the original.
The second question is what was the source. It seems clear that there was a source that Matthew and the writers of Mark and Luke drew from. The similarities among these gospels are just too striking in too many places for there not to have been a common source. Not only so, but that source had to have been a document (or oral tradition) in the Greek language; the Greek texts of these shared narratives are simply too close to allow for each author translating from Aramaic.
It is also clear that the source (unless there were multiple sources) was used by all three authors but selectively. That is, in some instances Matthew and Mark include a particular pericope such as the calling of Peter and Andrew in Matthew 4:18-22 and Mark 1:16-20 - which are virtually word for word the same in the Greek - but Luke does not. In other instances, Matthew and Luke share a piece, such as the details of the temptations in Matthew 4:1-11 and Luke 4:1-13, that is completely absent from Mark.
That similarity between Matthew and Luke has led some Bible scholars to hypothesize a two document source, Mark plus a document which is no longer extant called Q. (Q means source.)
In either case, Mark is regarded as prior in time to Matthew. I've come to a different conclusion. I believe that Matthew was the first of the four accounts of Jesus' life (including John) contained in the New Testament. I recognize that there is a common source, of course, but I've come to the conclusion that source was the "teaching of the Apostles" which is mentioned in Acts 2:42, "All the believers devoted themselves to the apostles’ teaching, and to fellowship, and to sharing in meals, and to prayer."
The teaching of the Apostles must have been oral at first. It must have included the things that Jesus said and did. It likely was in Aramaic, for that was the common language of the Jews in Jerusalem gathering as believers in Jesus in those early days. But as the group of believers grew, and especially as it began to include believers who were not Aramaic speakers but Greek speakers, the teaching of the Apostles would have had at least a second version in Greek. It is likely, also, that as time went on this oral narrative would have been written down, thus making it more or less settled in form and accounting for the similarities in the three gospel quotes from that source.
That accounts most logically and biblically for the source of all three synoptic gospels, Matthew, Mark, and Luke. It also accounts for the rougher literary quality of Mark, since these "sayings" were probably not polished pieces of writing and not yet connected in a larger narrative such as the gospels.
There is one more puzzle, however. Papias wrote that Matthew originally wrote in Hebrew (perhaps he meant Aramaic). If that were so and if the Gospel of Matthew is a translation into Greek (by Matthew or by someone else) why are there no indications in the text of translation? Translation is a creative process. No two translations of the same text by different translators will be the same. Certainly, the similarities among the three gospels are such to preclude that Matthew is a translation. They all must be using the same source, and that source must have been in Greek.
The solution is Matthew. Matthew was at least bi-lingual and probably tri-lingual. He was a tax collector. He would have spoken and written well in Greek and Aramaic. And he was a Levite, evidenced by the name which Mark and Luke use for him of Levi. That implies he was well acquainted with the Hebrew Scriptures and able to both read and write in Hebrew, for that was the education of the Levites.
It is likely that Papias was right: Matthew did write his gospel narrative first in Hebrew. In that case, he had available to him the Aramaic version of the teaching of the Apostles - which he would have had a part in compiling since he was present and was one of the twelve. But his second, the Greek text we have, was not a translation. It was a rewritten version, composed in Greek using the Greek version of the teaching of the Apostles - which the other two writers, Mark and Luke, also used.
This logical and biblical approach to the Gospel of Matthew enables us to see the gospel as the work of an eyewitness to Jesus' life and to the priority which the earliest Christian writers affirmed.