Ah, this sounds too much like the scratching of nails on a blackboard to anyone who knows anything about these matters!
Why are these people so utterly predictable? Why not start with the idea that Jesus was originally understood to be God come down from heaven? It's almost like all these believers secretly suspect that the claims of divinity associated with their Savior might all be attributable to the stupidity of the ancients and their tendency to exaggerate.
While it is true that a similar thing happened with Muhammad (i.e. that 'exaggerators' came along) I am not so sure that Christianity was developed around a historical person. In the end it doesn't matter of course. It is impossible to conceive of Christianity without these divine 'exaggerators.' Christianity begins with Jesus's death and it assumes - perhaps from its very beginnings - that this event had profound theological significance. Indeed, that it was the most significant event in the history of the world.
Yet doesn't a historical event require a historical Jesus? Not necessarily. It all comes down to why Ephem insists the Marcionite identified Jesus by the name Isu. Is Ephem imitating the fact the Marcionites spoke Greek or went out of their way to preserve the Greek Jesus in Syriac (i.e. Isu = Iesous)? Or is it because the Marcionites refused to identify him as someone named Joshua? Even Clement denies this identification so it wasn't just the Marcionites.
The bottom line is that I am certain that by the second century at least there were a large number of Christians who understood Jesus to be 'all God' with absolutely no humanity. I am also certain that for every Catholic writer who assumes that Jesus was both God and man there was lurking in the background two hostile heretical traditions he was very aware of - one who assumed that Jesus was exclusively human and the other which assumed that Jesus was all God. The Catholic tradition is necessarily secondary because it begins with an ecumenical compromise between these two antithetical poles.
Even though I recognize that there was a 'Jesus was man' tradition and that it may well have been 'Jewish' (the evidence indicates this is so) I also admit that there isn't enough information out there for us to even begin to understand what this tradition actually believed. It is far removed from everything associated with Paul, which make us at first suspect that it is associated with Justin Martyr who doesn't seem to be aware of the Pauline writings or rejected them as spurious. More on this later.
As such we are left with the 'Jesus is God' traditions which are necessarily pre-Catholic (owing to the fact that the Catholic tradition is as aforementioned an ecumenical compromise between this and the other tradition) and necessarily Pauline. The 'Jesus is God' tradition included the Marcionites, the Valentinians and possibly the Basilideans. In other words, traditions within Christianity which seemed to be identified with 'real' historical Christian teachers (with the Ebionites, Carpocratians, Ophites, Elkasites and the like the identification isn't always as certain).
Yet can we take matters one step further? Can we finally stop using meaningless terms like 'Jewish Christian' and 'Ebionite' and identify Justin Martyr as the earliest historical opponent of the 'Jesus is God' tradition? Look carefully at Irenaeus's statement in Book Four of his Refutation:
But if Christ did then [only] begin to have existence when He came [into the world] as man, and [if] the Father did remember [only] in the times of Tiberius Caesar to provide for [the wants of] men, and His Word was shown to have not always coexisted with His creatures; [it may be remarked that] neither then was it necessary that another God should be proclaimed, but [rather] that the reasons for so great carelessness and neglect on His part should be made the subject of investigation. For it is fitting that no such question should arise, and gather such strength, that it would indeed both change God, and destroy our faith in that Creator who supports us by means of His creation. For as we do direct our faith towards the Son, so also should we possess a firm and immoveable love towards the Father. In his book against Marcion, Justin does well say: "I would not have believed the Lord Himself, if He had announced any other than He who is our framer, maker, and nourisher. But because the only-begotten Son came to us from the one God, who both made this world and formed us, and contains and administers all things, summing up His own handiwork in Himself, my faith towards Him is steadfast, and my love to the Father immoveable, God bestowing both upon us." [Irenaeus AH 4.6.2]
It is only because all of us are so used to projecting our own assumptions on the Patristic material we study that we assume that Justin is saying that Jesus was the Creator. Yet the text doesn't say this. It only reinforces that the 'only begotten Son' came from the Creator rather than to announce another god beside the Creator.
We assume that Justin must also have assumed that Jesus was also the Creator. Yet 'only-begotten Son' isn't usually a divine title in the Jewish religion. Indeed Hebrews 11:17 uses it as a title for Isaac. Justin may well have only assumed that the Jesus was a wholly mortal spokesman for the Creator. It is well established that Marcionitism is the assumption that Jesus announced that his father was unknown and not the Creator. Yet if the Marcionites assumed that Jesus was wholly divine, how is it possible that they held that the Marcionites held the existence of two unknown Gods - i.e. the Father and the Son? Why isn't the most likely scenario that the Marcionites envisioned Jesus as the repentant Creator announcing his acceptance of a God higher than himself?
dating back to conversations with his grandfather, Gaston Frank. "He said we represent one of the last descendants of the Frankist Jewish faith in the world," he muses. "I grew up thinking that our family was something like the Last of the Mohicans."