The book of Elchasai is a work of literature considered to have first defined the movement as a separate religious phenomenon. Thus, the actual prophet may have been present earlier, creating the Nazarenes, whereas the Book of Elchasai and the Elchasaites would possibly be a divergent phenomenon.
I have had a suspicion which is that radical, violent, zealous "Jamesianism" from the Jewish War continued in the Kitos War. Rome's response ended zealotry as a particular movement.
What I have just learned, or integrated, is that the Book of Elchasai - a work of prophetic revelations - and even an associated set of gospel texts, was specifically a product of the Babylonian Jewish response to the Kitos War.
I have previously mentioned that I believe that Osroes I of Parthia had been the son of Izates of Adiabene, and the Jews of Transjordan, Nisibis and the community in Arbela rose up against Trajan's invasion especially because of messianic beliefs about Osroes.
The fact that Elchasaitism is a direct reaction to their loss in this war is extremely important. Recall that with the temple's destruction in 70, 115 was within the scope of immanent eschatology. They had every reason to interpret the uprising as God's redemption in the face of the fall of the temple, especially because this set was apparently very unhappy with how the temple had been managed before its destruction.
One of the few mentions of Elchasite practitioners was by Hippolytus of Rome who quotes Alcibiades
I would like to advance this moment in time as the birth of Christianity. This explains the confounding of history by the Biblical narrative, reconciling mythicist and historicist positions. The post-Kitos reaction reinterprets first century history.there was preached unto men a new remission of sins in the third year of Trajan's reign.
Instead of anticipating the Christ, now they find him within a figure they had previously rejected, itself a fulfilment of prophecy.
I also believe Kitos was the inspiration for the Pauline literature in the West.
We find a parallel in the execution of James by Ananus ben Ananus with the conflict between James and Paul. Theudas, whom I identify as Izates, was said to have been taught by Paul. In this light, Paul would be Ananus the senior. And Ananias was said to have converted Izates to Judaism by Josephus (though Eleazar, probably Boethus, radicalized him).
In this sense, the Pauline and Gnostic strain might be associated with the Ananians. This locus could explain the Pythagorean elements within Gnosticism, due to the former's association with Carmel. I am still struggling to determine the precise affiliation of the Ananians, though I assume they are fully aligned with the Alexandrians. It's also strange to think of Essenes as High Priests of the temple, but then again that in and of itself could explain a few things about what's going on in Judea particularly with the rebellions of Judas of Galilee.
This could suggest the Essene/Nazorean split parallels the Pauline/Jamesian and even Gnostic/Ebionite split.
In any event, the locus surrounding the Book of Elchasai is just too strong. We should consider Kitos War as the inception of an acceptance that Christ had already come. Not at that time, but earlier. Thus, the difficulty in reconciling the mythicist and historicist opinions. Christ did not come at the time when people first stated believing that he had come. Thus the historical inspiration for Christ had no direct connection to the originators of the sect preaching him, which would certainly confound historicism.