(Just occurred to me that I hadn't actually gotten around to writing this one.)
So, there is a semi-serious* inspiration to the Testament of Judas that came to me while I was writing my dissertation on the Gospel of Judas, which is an actual 2nd-century Christian text. It falls into the broad category of Gnostic Christianity, along with many other texts, such as the Gospel of Truth, the Apocryphon of John, and such ilk. Now, one opinion among ancient Christian proto-orthodox heresy-hunters was that the Gnostic Christians were writing their own texts to supplant the texts of the New Testament** and create their own scripture. Not a few modern biblical scholars seem to hold the same opinion.
However, I think that's wrong. The Gospel of Judas was not written to replace the New Testament gospels - it was written as a commentary on the New Testament gospels (in this particular case, I think it's a commentary on a specific theme the author of Gos. Jud. sees in the Gospel of Mark). I think the same can be said for all the Gnostic Christian texts. The four Gospels, along with Paul's letters, were extremely popular texts amongst all types of Christians almost from the get-go; where the disagreements come in is in how to read those texts. It's all about interpretation.
So the author of the Gospel of Judas reads Mark, and latches onto the statements about the Twelve, and that inspires him to write his gospel to emphasize and reinforce a message he sees in Mark that he thinks has been ignored until now ("now" being the middle of the second century CE). That got me to thinking about how whole theologies can hang on how one reads a particular theme, or how one reads a particular verse, even, which is where the Testament of Judas comes in.
Matthew 27:52-53 was the verse I latched onto for my interpretation of the canonical gospels, the lens through which I reread Matthew, Mark, Luke, and John (and a few other texts), interpreting that odd verse from Matthew as a zombie apocalypse. Obviously, there's a lot that gets left out when reading the gospels that way - there's no references to the Beatitudes in the Testament of Judas, for example, and many of the parables get left out as well. On the other hand, my interpretive lens has much more to hang on than, say, proponents of the Prosperity Gospel, because it's much harder to make Jesus look like a 21st century neoliberal economist than it is to make him look like an evil necromancer, based solely on verses from the New Testament.
Anyway, that's the semi-serious side to the Testament of Judas. Apologies for having you wait more than two years for the explanation.
* Semi-serious, because really, it's a zombie apocalypse story about necromancer Jesus, how serious can it be?
** Or the texts that would become the New Testament, since it was a couple of centuries at least before the NT canon was settled upon by most Christians.
