This post is useful: What texts are open for examination?
This is a site about Bible. If on a different site geared specifically toward Pseudepigrapha of any kind, tags per book or even fragment could be easily regarded as on topic. Here however, 1. it is likely that there would not be many more tags than so-tagged posts, and 2. the writings in question are only partially (previously deemed tertiarily) on topic as this is not a site dedicated to those works.
There are other places to discuss how, when, and why tags are set as they are. Those discussions have more precedence on tag creation than specific matters of the writings themselves; tags are about being on topic and orderly. A group of tags created to apply to very few posts that only relate as a tertiary topic is not orderly.
Per the main question, are these writings on topic?
The answer and manner of handling these would not only apply to the Gnostic Gospels, but to any Pseudepigrapha.
The Gnostics are Pseudepigrapha, along with others
In biblical studies, it refers to a collection of ancient Jewish books attributed to the patriarchs or other important figures from the Bible, but not actually written by those authors. To make that clearer, here are three classifications that biblical scholars use:
There are the 39 books that fit into the Old Testament, also called the Hebrew Bible or The Tanakh. These books are considered inspired Scripture, as are the 27 books that make up the canon of the New Testament.
Then there is the Apocrypha... The Roman Catholic Church, the Eastern Orthodox Church, and a few other groups regard the Apocrypha as Scripture but Protestants consider it useful but not inspired. Martin Luther reportedly said the Apocrypha “are books which are not considered equal to the Holy Scriptures but are useful and good to read.”
The Pseudepigrapha are books written in the same period or later than the Apocrypha, but they are not included in the Septuagint and with a few exceptions haven’t been regarded as inspired Scripture. Some of these works claim to include the full story of something mentioned in the Bible—for example, the Apocalypse of Adam describes a vision that Adam reportedly had and passed on to his son Seth.
The so-called “Gnostic Gospels” which claim to be written by Peter, Thomas, and other disciples would fit that definition.
What can make a Pseudepigrapha question on-topic?
If the question presumes that a non-canonical text is non-canonical.
- We may be curious about authorship of a Gnostic Gospel and contrast it to canonical Gospels.
- We may be curious about content differences.
- We may even be interested in understanding the text in its original language.
But, these would not be questions about a "Biblical" text. Rather, they would be questions contrasting a Biblical text.
In the case of Thomas, the original language would be Coptic. This may raise the question of whether Thomas language questions are off topic because its original language was not any of the original languages of canonical manuscripts. But, it would be okay as long as it was intended to understand the meaning of a specific passage, not an excuse to learn Coptic. And, that stands for Biblical languages as well. To learn a language, one should go to an SE site specific for that language, or to Linguistics.SE.
As long as we retain the pre-existing definition of 'Biblical'
This was discussed at length by some of the founding and original users of this site.
Biblical Text is "Christian" and "Jewish", which would include the Catholic Apocrypha, as long as it is treated as such.
The big issue here is not to misrepresent known definitions. The Biblical Hermeneutics site is not a place to misrepresent facts and existing definitions so as to disseminate disinformation to novice students because one does not have strong enough arguments to grow a following some other way. It's not an unreasonable concern because it happens all the time. The Chinese government told Bill Hybels in 2010 that "cults" were one of the main reasons for such excessive regulation for Christian churches—because non-mainstream teaching presented as if it were mainstream is a problem across the world in many sectors of society, and it was indeed a major problem in China and still is. Our discussions on any SE site, as should be with any responsible, academic discussion, need to accurately represent the various concepts, definitions, and categories that they are comprised of.
Gnostic Gospels and other Pseudepigrapha are not in traditional canon for good reason. We're not going to start pretending that they are. As long as we are forthcoming and not pretending, we should be okay.
Statements like these would make a question off topic:
- I think this should be in the canon. (Canon recommendations are off-topic.)
- In the New Testament book, The Gospel of Thomas... (No, it's not.)
- In the Protestant Bible, The Book of Enoch says... (No, it's not.)