The Gospel of Matthew:
"
The unknown author, whom we shall continue to call Matthew for the sake of convenience, drew no only up the Gospel according to Mark but upon a large body of material (principally, sayings of Jesus) not found in Mk that corresponds, sometimes exactly, to material found also in the Gospel according to Luke.
(The New American Bible, ISBN: 978-0-529-06484-4, Page 1008)"
"As for the place where the gospel was composed,
a plausible suggestion is that it was Antioch, the capital of the Roman province of Syria.
(The New American Bible, ISBN: 978-0-529-06484-4, Page 1009)"
So we clearly see, both the author or authors and the place of composition of the "Gospel of Matthew" are unknown.
The Gospel of Mark:
Note: This gospel is the oldest and supposedly the most original one in the New Testament!
"
Although the book is anonymous, apart from the ancient heading "According to Mark" in manuscripts,
it has traditionally been assigned to John Mark, in whose mother's house (at Jerusalem) Christians assembled.
(The New American Bible, ISBN: 978-0-529-06484-4, Page 1064)"
"
Although there is no direct internal evidence of authorship, it was the unanimous testimony of the early church that this Gospel was written by John Mark.
(From the NIV Bible Commentary [1], page 1488)"
- We certainly do not know whether Mark was the author or not! The quote clearly states "no direct internal evidence of authorship". Also, the so-called unanimous testimony of the early church:
- Does not prove that the author was Mark.
- Nor does it prove that other people did not alter and modify the book, especially when the book was written at least 40-50 years after Christ. We don't even know if Mark even wrote the book.
"
Traditionally, the gospel is said to have been written shortly before A.D. 70 in Rome, at a time of impending persecution and when destruction loomed over Jerusalem.
(The New American Bible, ISBN: 978-0-529-06484-4, Page 1064)"
"Serious doubts exists as to whether these verses belong to the Gospel of Mark. They are absent from important early manuscripts and display certain peculiarities of vocabulary, style and theological content that are unlike the rest of Mark. His Gospel probably ended at 16:8,
or its original ending has been lost. (From the NIV Bible Foot Notes [1], page 1528)"
"This verse, which reads, "But if you do not forgive, neither will your heavenly Father forgive your transgressions,"
is omitted in the best manuscripts. (The New American Bible, ISBN: 978-0-529-06484-4, Page 1081)"
"This passage, termed the Longer Ending to the Marcan gospel by comparison with a much briefer conclusion
found in some less important manuscripts, has traditionally been accepted as a canonical part of the gospel and was defined as such by the Council of Trent. Early citations of it by the Fathers indicate that it was composed by the second century, although vocabulary and style indicate
that it was written by someone other than Mark. (
The New American Bible, ISBN: 978-0-529-06484-4, Page 1088)"
So, in reality, we don't really know whether Mark was the sole author of this Gospel or not,
nor do we know when and where the "gospel" was even written. And since The New Testament wasn't even documented on paper until 150-300 years (depending on what Christian you talk to) after Jesus, then how are we to know for sure that the current "Gospel of Mark" wasn't written by some pro of Mark?