As I understand it the so-called “Gospel of Judas” and ALL of the so-called “Gnostic Gospels” were written more than a century after the crucifixion. While one can debate whether or not the New Testament is absolutely reliable, the idea that extremely obscure texts written more than a century later (by people who had absolutely no first-hand knowledge of any of the events of the life and death of Jesus Christ) should be given any great credibility is just another dogma of politically correct debunkers. There is a great rage for pretending that convenient novelties are important when they serve a particular (liberal-secular) point of view. I would not give “The Gospel of Judas” any more credibility than Dan Brown’s “DaVinci Code” (the latter has been thoroughly discredited).
There were many writings circulating in the few centuries after Christ. This created confusion, and people called for the Church to produce a canon of what is accepted scripture. This was done by the fourth century. The reason that the gnostic gospels did not get included in the canon is that they were considered faulty in some way.
It is odd that after 1600 years, people want to consider the gnostic gospels more reliable than the texts the people closest to the events did. And the sole reason they consider them authentic is that the early Church thought they were defective.
The latter, having been (and indeed labeled as such, by the author) a work of fiction, it is not possible to "discredit" it. Perhaps what you meant to say was that some of the "theory" underlying the fictitious work has been discredited (ie, "Holy Blood, Holy Grail", and the Mary Magdalene as wife/consort of Christ, etc...)
the infowarrior
There is a whole cottage industry generated by the interest in the gnostics. But the main interest in discrediting orthodox Christianity by pointing out the existence of these other ‘gospels” which are, as it says, parodies of the real things.
The Gnostic Gospels were written to further the cause of those who were followers of this particular type of cult Christianity. The same types are now trying to use it to further their own purposes.
Mel
More like a century and a half. All of the gnostic gospels date from the late second century.