Most biblical scholars long ago came to the conclusion that the gospels of Matthew, Mark, Luke and John were originally anonymous, and that we don’t have a clue who wrote them. As you can imagine, this poses a pretty severe threat to people who are committed to believing that everything they say is true. A few biblical scholars even fall under that category, and as you may already have guessed, they disagree with the conclusion. So, how do we know that the gospels really are anonymous? Are the objections raised by critics any good? Here’s how we know: “Because our surviving Greek manuscripts provide such a wide a variety of (different) titles for the gospels, textual scholars have long realized that their familiar names (e.g. ‘The Gospel According to Matthew’) do not go back to a single original, but were later added by scribes.” p.248-249 Bart Ehrman, Jesus: Apocalyptic Prophet of the New Millenium. As far as I know, none of these titles have different names (i.e. we never find what we’d recognize as our gospel of Matthew being ascribed to Luke or vice versa) but I think what Ehrman means is that the gospel titles vary in ways like this: one manuscript says “The Gospel According to St. Matthew” another says “The Gospel of St. Matthew.” That’s the kind of variation he’s talking about, I think.
Ehrman also mentions in a number of his writings that no one would write a title like that if they had written the book. Example: I’m not going to write a blog post with title “Gospels are anonymous according to Nicholas Covington” I’d write “Gospels are anonymous, by Nicholas Covington” or something like that. Hence, the ‘according to’ inscriptions strongly indicate that someone else put that title there later, not that it was part of the original.
Why are those inscriptions there? The churches had traditions about who-authored-what in the old days, and the natural next-step for the apologists to take is to argue that the church traditions are reliable. Uh-uh, says Ehrman:
“None of the gospels claim to be written by an eyewitness. Take Matthew, for example. Even though someone named Matthew is mentioned in Matthew 9:9, there’s nothing in that verse to indicate that he’s actually the person writing the account (read it and see!). Furthermore, nowhere in the entire gospel does the author indicate that he was personally involved in the events that are described. He never says, for instance, ‘one time Jesus and I went up to Jerusalem, and while we were there…’ Instead, he always writes in the third person-even about the disciple Matthew!” (p.42 Jesus).
A number of other considerations weigh in against the probability of eyewitness authorship, including the fact that 3 of the 4 gospel authors seem to have heavily copied from earlier written sources (why would anyone do that if they experienced the events themselves, or had heard about it from a close friend?). I think it is sufficient to stop there. Most biblical scholars just don’t buy into the eyewitness authorship hypothesis, including a great number of conservative Christian scholars. Now you know that there are good reasons they don’t, it isn’t just prejudice or wild guesswork driving these conclusions.