[quote=@Nilesapa]
A question about the nature of Islam in this timeline:

Given the rise of islam happened in the context of a still prominent Roman Empire, wouldn't this cause serious butterflies to the faith, if it even exists?  Islam may in this world have come to being by a different prophet from a different tribe even if Islam in these sense of being a unifying faith among the arabic tribes derived from judeo-christian thought still is around.  While they likely still will write in Arabic and some of the athestetics may be similiar (although I don't know if there will be mosques modelled after muhammed's house as there will in our world), the whole doctrine may be different from the Sunnis and Shias or those other schools of thought that fell into the wayside.  From a doctrinal standpoint I wonder if Islam at this point might as well be a "build your own Abrahamic faith"-type deal.

I have interest, but unsure where to go.  Although I do ask, are Knights a thing here?
[/quote]

Christianity still being a factor there would still be the Abrahamic ground-work for faith such as Islam to rise among the Arabs. And the only significant thing that'd be changing in the geo-politics of Arabia is the name of the Empire of Rome is not the Byzantine Empire. But the traditions of Rome may have changed in such a way to resemble Byzantium anyways. So it's really just a larger - and stretched - Byzantium.

Per any direct effects on Arabia: I don't think it would have been major. In-so-far as I know it's not like the Sassanids or the Romans offered patronage to Mohammad or any of his rivals. The only tangible effect I can see happening is merely the inspirational unifying aspect of Islam as a religion for the Arabs. The only significant changes that would be made to Arab culture would come into effect only when they start taking land. Instead of Greek influences in architecture and ad-hoc'ing local words for administrative positions (like tax-collector) it'd be replaced by some borrowed and transliterated Latin. Different languages too may be favored for translations of Roman writing into Arabic. But at this early stage, there wouldn't be much direct effect of this Rome to the Arabs.