Here is my conclusion of my blog post:
http://historical-jesus.sosblogs.com/Hi ... 1-p105.htm
It seems to me the original Greek text was entirely Jewish and then slightly interpolated (9:14,16) by a Christian. Then two interpolators, separately, on two different copies, added more different additions/insertions, some of them overtly Christian in nature. These two resulting copies may have been furthermore interpolated.
The original Greek text, even after being added on with its few "tentative" Christian-like interpolations, did not have "Son", "first-begotten", "Jesus" or "Christ" in it.
Therefore, I think the ascent of Isaiah and descent & then ascent of the Beloved were not originally Christian. But later, probably in the 2nd century, when Docetism was adopted among some Gnostic Christians, the original Jewish Greek text got manipulated in order to serve the Christian cause.
I know that this thinking is very much far removed from Dr. Carrier's observations in OHJ on 'the Ascension of Isaiah':
The 'they' who will think he is a and not know who he is and kill him are only ever said to be Satan and angels. No other subject is mentioned for that pronoun, nor is any other implied. God clearly intends Jesus to do nothing more than go to the firmament, and for no other reason than to be killed by Satan and his sky demons, rise from the dead and conduct affairs there for over a year (doing what, it's not said), and then ascend to heaven. In other words, instead of conducting a ministry on earth, Jesus is commanded to go straight to the end and die, and rise from the dead, and then remain where he had for a year and a half (9.16; cf. 10.12-14; although the duration is omitted some versions), and then ascend to the heavens. The 'tree' on which is crucified (9.14) is thus implied to be one of the 'copies' of trees that we are told are in the firmament (7.10).
Of course, even with all its (highly suspected) interpolations, the text of 'Ascension of Isaiah' does not say what I bolded from page 41 of Carrier's 'On the Historicity Of Jesus' (OHJ). This is just pure speculations.
Furthermore, Paul indicated Jesus' crucifixion happened in the heartland of the Jews, among Jews:
http://historical-jesus.sosblogs.com/Hi ... b1-p22.htm
Cordially, Bernard