Okay I can't stop thinking about a world where the primary theological issue between the "Big Three Abrahamic Religions" is a single, two-part coherent question about the applicability of a specific body of religious law and a specific individual's place in it, instead of a series of different and incompatible questions that makes the very idea of "Abrahamic religions" contentious to some.
Like, Bart Ehrman wrote about the OTL "Two Powers in Heaven" theology in pre-Hurban Judaism. In a world where Christianity is both not fundamentally antisemitic and is adoptionist and dyophysite instead of trinitarian, I can imagine that Two Powers theology might not die out. Instead of Judaism being opposed to Christianity because it appears foundationally polytheistic, it would simply disagree with Christianity on the identity, but not necessarily the nature, of the Messiah.
(That's not to say there wouldn't be a fierce rivalry between the three religions! And I'm not saying that there wouldn't ever be violence! What I am saying is that there is the potential for the kind of tense-but-inherently-peaceful interfaith relationship we see between Christians and Jews in post-enlightenment America or prewar Poland, and between Muslims and Jews in Umayyad Iberia, to be the norm across history instead of anomalous!)
Judaism: the Messiah is not yet here and Mosaic law still applies
Arab Christianity / !Ebionites: the Messiah is here and Mosaic law still applies
Persianate Christianity / Apostolic Church: the Messiah is here and Mosaic law no longer applies
These are debates that could, in theory, allow a common religious identity to be maintained despite doctrinal differences, without a gross hierarchical nature to it (as we see between the supersessionism of OTL Christianity and Islam). Like how Catholic, Orthodox, Coptic, and (some) Protestants see one another as fundamentally sort of the same. Or how Sunni and Shia see one another. Or how the first Christian Persian emperor OTL proclaimed Judaism, Christianity, Zoroastrian, and Mandeanism to be all fundamentally sort of the same.
I dunno. Maybe it's just me. But it seems like there's a possibility for these three movements to maintain some dialogue that looks a little nicer than OTL.