Most of these theories are quite silly and can be waved away. But it got me thinking: is there any reason why an Evangelical would accept that the four Gospels were actually written by Matthew, Mark, Luke and John? After all, none of the four Gospels state who their author is. The closest we get is John's Gospel, in John 19:35,
The man who saw it has given testimony, and his testimony is true. He knows that he tells the truth, and he testifies so that you also may believe.But that only establishes that the Gospel is based upon John's eyewitness testimony. It doesn't necessarily prove that St. John wrote it himself, or whether this was a disciple of John recording his oral testimony. In fact, the authorship of the Fourth Gospel is the most hotly debated point. Likewise, from Luke 1:3-4 and Acts 1:1-2, we can see that the same man authored both, and wrote them for "Theophilus."
The Church Fathers on the Authorship of the Gospels
So taking the Bible alone, we can't say who wrote the Gospels. Looking at the writings of the Early Church Fathers, however, we can. St. Irenaeus of Lyons addressed the issue of the authorship of the Gospels in Against Heresies in 180 A.D. From Book III, Chapter 1:
In about 207 or 208 A.D., Tertullian wrote that the Gospels were all written by Apostles (in the case of Matthew and John), or students of the Apostles (in the case of Mark and Luke). From Book IV, Chapter 2 of Against Marcion:Matthew also issued a written Gospel among the Hebrews in their own dialect, while Peter and Paul were preaching at Rome, and laying the foundations of the Church. After their departure, Mark, the disciple and interpreter of Peter, did also hand down to us in writing what had been preached by Peter. Luke also, the companion of Paul, recorded in a book the Gospel preached by him. Afterwards, John, the disciple of the Lord, who also had leaned upon His breast, did himself publish a Gospel during his residence at Ephesus in Asia.
In Book III, Chapter 24 of Eusebius's Church History (written in the early 300s, and based in large part on much earlier sources), we hear:We lay it down as our first position, that the evangelical Testament has apostles for its authors, to whom was assigned by the Lord Himself this office of publishing the gospel. Since, however, there are apostolic men also, they are yet not alone, but appear with apostles and after apostles; because the preaching of disciples might be open to the suspicion of an affectation of glory, if there did not accompany it the authority of the masters, which means that of Christ, for it was that which made the apostles their masters. Of the apostles, therefore, John and Matthew first instill faith into us; while of apostolic men, Luke and Mark renew it afterwards.
Nevertheless, of all the disciples of the Lord, only Matthew and John have left us written memorials, and they, tradition says, were led to write only under the pressure of necessity.Likewise, he cites Luke as the author of Acts in Book II, Chapter 11 and elsewhere.
For Matthew, who had at first preached to the Hebrews, when he was about to go to other peoples, committed his Gospel to writing in his native tongue, and thus compensated those whom he was obliged to leave for the loss of his presence.
And when Mark and Luke had already published their Gospels, they say that John, who had employed all his time in proclaiming the Gospel orally, finally proceeded to write for the following reason. The three Gospels already mentioned having come into the hands of all and into his own too, they say that he accepted them and bore witness to their truthfulness; but that there was lacking in them an account of the deeds done by Christ at the beginning of his ministry.
Can Evangelicals Rely on These Accounts?
There are plenty more sources as well, but the point is clear. The early Christians were quite adamant that Matthew, Mark, Luke, and John were the Gospel writers. But here's why that's tricky for Evangelicals. In Book II, Chapter 15, Eusebius explains that Mark was a follower of Peter's from his time in Rome. And St. Irenaeus says that Matthew wrote his Gospel "while Peter and Paul were preaching at Rome, and laying the foundations of the Church."
But Evangelicals often deny that Peter was ever in Rome, and almost universally reject the theory that the Church has its foundations in Rome. After all, conceding that the Church is (a) Petrine, and (b) Roman goes a long way towards establishing the papacy. So instead, a rather large Evangelical camp treats the Early Church Fathers with suspicion (and sometimes, as outright frauds and heretics), precisely because they're so Catholic. For example, here's Dave Hunt and T.A. McMahon explaining why you shouldn't spend your time worrying about what the Church Fathers say, and here's John Piper claiming that the Church from 100 A.D. onwards is unreliable, so "We are in a better position today to know Jesus Christ than anyone who lived from AD 100 to 300." And that doesn't even count the folks like Ed Stevens, who claims that all the true Christians were raptured in 70 A.D.
So to the extent Evangelicals reject the Church Fathers, they're cutting of the branch on which they're sitting. Without the Fathers, you can't say who wrote the Gospels, or whether the Gospels were considered orthodox by the early Christians, or whether they were considered inspired Scripture. Almost everything we know about the Bible comes to us from the Fathers.
Of course, I'm not suggesting you have to think that each of the Fathers is 100% right on everything (nobody takes that position, as they occasionally disagree). Nor am I saying that it's particularly important to the Faith who wrote the Gospels -- I'm just using it as an example of something almost all Evangelicals believe about the Bible, but which they're not getting from the Bible itself. My point is simply this: without the Church Fathers, there's no particular reason to trust that we have the correct Books of the Bible, and no particular way to know anything helpful about who wrote those Books, such as whether the writers were honest and orthodox.