The Gospel narratives are not signed, so how do we know that Matthew wrote Matthew and Luke wrote Luke etc.? Paul usually signed his epistles, but none of the Gospel narratives are signed by their authors. What gives? How do we know who wrote what? So goes the argument I receive on the discussion boards that challenge the Christian faith. Nevertheless, the question has been asked. Do we have an answer, and does this answer support the tradition that Matthew did, indeed, write Matthew and so on for the other Gospel narratives and their authors?
Two early Christian traditions come from Papias and Irenaeus, church fathers of the 2nd century CE. They write that Matthew was first written in Hebrew dialect which may mean Aramaic which is believed to be the language of the Jews at that time. They also wrote that Luke authored his Gospel, and Mark wrote a transcript of Peter’s sermon / Gospel that he spoke before the Christian congregations in Rome. After all these were written John wrote his spiritual Gospel.
How do we know that Papias and / or Irenaeus are correct? I believe this is a legitimate question, and it is often asked on the discussion boards that challenge the Christian point of view. Well, the only evidence we have is circumstantial. We do not have any other tradition that would stand against what the early church fathers claim. In other words no one in antiquity claims Andrew wrote the Gospel we know as Matthew, nor has Philip written Mark etc. All the traditions we have support the claims of Papias and Irenaeus, and this would be quite odd, if it weren’t true. For example, there are varying traditions in ancient writings attributed to Christians that Mary was a virgin all her life, and Jesus was her only son, Jesus’ brethren being either cousins or brethren from a previous marriage of Joseph. There are also traditions that Pilate became a Christian, and I could cite several others to make my point. However, there are no such different traditions that would contradict Papias’ or Irenaeus’ statements about the authors of the Gospel narratives.
There is also a logical argument that would support their testimonies. Most ancient writings were written on scrolls, and scrolls were expensive to write and copy, so good maintenance was of the utmost importance. In the great libraries, for example, the scrolls were kept out of sunlight by putting them into slots in a case which usually was built into the wall of the building. There was also a lid / door on the case that helped to keep out the light. Additional care was needed to identify the work without unnecessarily handling the scrolls. So, tags were attached to each scroll in both large and small libraries so the reader could identify the scroll and its author without opening each scroll and reading the first few lines to identify the work.
This is also what the Christians did. Their small libraries might involve one or more cases, which were mobile enough to keep in an elder’s home and carried wherever they were needed. The tags or tituli, as they were called, would hang from the opening end of the cubicle in the chest so the reader could readily access the correct scroll for the current reading. Notice:
“…The scroll when finished was rolled round a staff, and thus called volumn. It was usual to write only one book of a work on one such scroll, thus, infr. 117, Ovid speaks of the fifteen books of the Metamorphoses as mutatae, ter quinque volumina, formae. The ends of the staff (which did not protrude beyond the ends of the scroll) were painted, and from their resemblance to the human navel were called umbilici; but where greater finish was desired, bosses or knobs were attached to the ends of the umbilici, which were called cornua. The fronts, or edges of the two extremities of the roll around the cornua, were cut and smoothed with pumice stone (pumex). The lettering-piece containing the title of the book (titulus or index), was written on a narrow strip of parchment of a deep red color (minium), and fastened to the centre of the scroll, so as to hang down outside (Rich. s.v. index); though sometimes it was affixed to one of the umbilici, so as to hang from one of the fronts (infr. 109, Guhl and Koner, p. 532). Occasionally it was tied to the membrane, the exterior parchment case into which the roll was put to protect it from injury, and which was stained with a purple (vaccinium, l. 5), or sometimes yellow colour (lutum)…” [OVID; TRISTIA BOOK 1; Introduction & Notes by S.G. Owen, B.A.; Oxford (Clarendon Press, 1885). See APPENDIX. I. 5 ff.].
Another source worthy of consideration is:
Literary references as well as archaeological evidence help us to reconstruct and understand ancient library shelving systems. Shelving systems consisted of a niche or hole in the wall that held either shelves directly in it or was large enough to hold a storage cabinet, called an armaria. Armaria had doors to protect the books from damaging light. In larger libraries they were built into the walls. Books in the armaria were arranged in alphabetical order by author and the “finding facilitated by the tituli hanging from the rolls” [Ancient Libraries of Greece and Rome; “A Summary of Research Findings 1999” by Jacalyn C. Spoon, (under the heading: “Shelving Systems”)]
Irenaeus was a student of Papias and testified of two of the four Gospels being written by the very same authors named by Papias. However, instead of his testimony being a mere copy of his teacher, what Irenaeus wrote has been regarded by some to show what would normally be expected to be found on the ancient tituli or tags attached to the scrolls. Thus, it is very logical that ancient Christians identified the scrolls of the apostles in just this way, so they were able to access the correct scroll without any trouble in the book-cases and without unnecessarily chancing the other scrolls to damage. Thus, this would be why there was never another tradition concerning the authors of our four Gospel narratives. The authors have never been mixed up, saying Matthew wrote John or John Mark etc. Neither was Thomas or Philip or Andrew or any other Apostle said to have written any of the Gospel accounts. This would be quite odd if the authors were truly unknown, especially since two of the Gospel authors are not Apostles.
 Claus-Jurgen Thorton, Der Zeuge des Zeugen: Lukas als Historiker der Paulusreisen [The Witness of the Witness: Luke as Historian of Paul’s Travels], ed. Martin Hengel, Wissenshaftlich Untersuchugen zum Neuen Testament 56 (Tubingen: Mohr [Siebek], 1991), pp 10-82. This work was cited in Misquoting Truth by Timothy Paul Jones (Inter Varsity Press, 2007), chapter 6, “Truth About the Authors of the Gospels”; p.104.