None of the Gospels in the Bible were written by the people whose names are in the title either.
There are issues with the gnostic gospels, beyond their titles.
Is The Gospel Of Thomas Authentic? | Reasons for Jesus
By James Bishop| The Gospel of Thomas is a text of Gnostic origin commonly dated to the first half of the 2nd century. The Gnostics were a religious group that postdated 1st century Christianity, and believed that humans are divine souls trapped in the ordinary physical world. One of the more popular of these texts is the Gospel of Thomas (GT). And what we’d want to consider is whether nor not the GT is just as valuable, if not more so, that our canonical gospels.
It seems that a minority of scholars, particularly those within the Jesus Seminar, want to date the GT text within the 1st century. In doing so they wish to give it equal value to the canonical gospels. We see this effort in their work The Five Gospels which, alongside the canonical gospels, includes the GT.
However, we shall review why this remains a minority view within professional scholarship.
Firstly, the GT seems to be dependent on the earlier canonical gospels (Mark, Matthew, Luke, John). We see this in sayings 10 and 16 which are seen to be redactions of Luke 12:49, 51-52 and Matthew 10:34-35.
This suggests that Thomas’ author (not Thomas the disciple) is either already aware of these two gospels in circulation or is borrowing from an even later redaction of these two sources. Either way Thomas comes later than the canonicals which should render some doubt pertaining to its value.
Secondly, the author of Thomas also seems to corroborate some sayings evident in the canonical Gospel of Luke. This suggests that Thomas must come after Luke, as well as after Mark. Most scholars hold to markan priority (meaning Luke consulted the earlier Gospel of Mark for his content), and this tells us that Thomas must be later than Mark, as well as Luke. Professor Craig Evans explains:
“OVER HALF OF THE NEW TESTAMENT WRITINGS ARE QUOTED, PARALLELED, OR ALLUDED TO IN THOMAS… I’M NOT AWARE OF A CHRISTIAN WRITING PRIOR TO AD 150 THAT REFERENCES THIS MUCH OF THE NEW TESTAMENT” (1).
Moreover, on various occasions we find that the GT is dependent on later Syriac translations of the canonical gospels. In other words, this suggests that the GT is based on the translations of our canonical gospels that were translated into other languages. One such example is saying 54 which follows the Syriac of Matthew 5:3 rather than the Greek of the same passage or the Greek of the parallel in Luke 6:20.
Also saying 65 – 66 contains the Parable of the Wicked Tenants but in the harmonized form of Mark and Luke we discover the early Syriac translations of which Thomas picks up. Scholar Klyne Snodgrass explains that
“Thomas, rather than representing the earliest form, has been shaped by this harmonizing tendency in Syria. If the Gospel of Thomas were the earliest, we would have to imagine that each of the evangelists or the traditions behind them expanded the parable in different directions and then that in the process of transmission the text was trimmed back to the form it has in the Syriac Gospels. It is much more likely that Thomas, which has a Syrian provenance, is dependent on the tradition of the canonical Gospels that has been abbreviated and harmonized by oral transmission” (2).
Then there is just the general lack of history that is problematic. Since the GT is a election of some 114 sayings alleged to have been said by Jesus, we find that there is a lack of any travel scenes, mentioning of cities or towns like Galilee or Jerusalem, miracles, healings, or exorcisms. There are essentially just sayings. This surely proves that the GT is less valuable than the canonical gospels as they at least report Jesus’ movements, miracles, ministry and so forth.
I believe that for these several reasons it shouldn’t be seen that the GT is of equal, or of more, value to our canonicals. A persuasive case dates that GT after the 1st century which is considerably later than our canonical gospels. It is furthermore apparent that it is dependent on content found within Luke and Matthew as well as later Syriac translations. The GT also lacks traces of actual historical data that we find within the canonicals.
Why we shouldn’t trust the Gnostic Gospels.