If you look at medieval Castilian and medieval Mozarabic they are relatively similar and IIRC were mutually intelligible. It's as Spanish as anything else in the tenth century.Well, Mozarabic Romance WAS written in Arabic script IOTL, though it wasn't really "Spanish", as in, Castilian.
However, it is quite unlikely that widespread use of Arabic letters can survive the Reconquista in good shape.
Are there other examples of Arabic script being used by non-Muslim non-Arabs (i.e. other than Arab Christians?)
I think it was too linked to survive any kind of Reconquista. But I may be mistaken, I suppose.
Arabic script is used in... Maltese I think?
Maltese did'nt have a uniform written system until the 20th century, though previously it was never written in Arabic, rather it was to a large extent an oral language, and the few times it was written down it was alwats in the Latin Script.
What I just found on Wikipedia:
Europe
مۉلٖىمۉ سه ته*بٖى بۉژه = Molimo se tebi, Bože (We pray to you, o God); see Arebica)
- Albanian called Elifbaja shqip
- Aljamiado (script used sometimes for Mozarabic, Berber, Spanish or Ladino)
- Azeri in Azerbaijan (now written in the Latin alphabet and Cyrillic script in Azerbaijan);
- Belarusian (among ethnic Tatars; see Belarusian Arabic alphabet)
- Bosnian (only for literary purposes; currently written in the Latin alphabet; Text example:
- Crimean Tatar
- French by the Arabs and Berbers in Algeria and other parts of North Africa during the French colonial period.
- Greek in certain areas and Greece and Anatolia
- Medieval Albanian
- Medieval Bosnian
- Mozarabic, Aragonese, Portuguese, and Spanish, when the Muslims ruled the Iberian peninsula (see Aljamiado)
- Ottoman Turkish
- Polish (among ethnic Lipka Tatars)
Remember that in all of those cases they're either places in South-East Europe that had/have large Muslim populations or are used by Muslim minority populations eslewhere.
They were pretty much all Muslim populations with the exception of the Mozarabic, which swapped to Latin after the 1400s.
It appears that it really is linked.
Pretty much, though their is an interesting thing to think of to; Nearly all Arabic scripts are used by Muslims (excluding Mozarabic and the Levantine Minority Religions), but not all Muslims use the Arabic Script (Indonesia and Malaysia use the Latin Script).
Turkey post-reform, as well. And naturally all the Russian Muslims and many Central Asian ones post-USSR. And Bosnians. Prestige, I suppose.