will it affect the development of Arabic language?
Probably. While I can see Arab being a sacerdotal language (as coptic or armaic), I would see an of course far less extended use of Arab worldwide, but radical linguistical changes as well.
Arab was, still is, believed the language that God used for delievering His word. It's why Qu'ran isn't used translated, why Qu'ranic language is that important. Butterflying that alone would be huge.
1) A less conservative Litterary Arab. For the sake of maintaining a continuity, administrativly, religiously, economically, culturally, etc. you had the permanance of quite a conservative language compared to Arab dialects.
A far less theologically important as well far less important geographical dispersion would allow changes in Arab languages to happen easily and more deeply
2) More important persian influence. Well, even more than IOTL. Remaining politically divided, and without great byzantine impetus to deal with Arabia unless by quite independent proxy, Arabia would probably remain in the sphere of influence of Persian civilisation or at least in its cultural sphere.
Meaning that concepts and words to express them would be important.
3) Less important hellenic influence. For the same reasons, and for that Islamic conquest really took on Byzantine and Post-Roman features, that influenced much Arab culture up to words (as falsafa)
4) Survival of Pre-Islamic poetry, a less religious based language would allow, critically in regions less concerned by Persian influence, to make an original Arab litterature to blossom.
