>>96036777I just tried to pull together all the facts myself for improving the Araby article on 1d6chan:
2e literally says they worship Allah in the corebook, although Mad Mullah Aklan'd supposedly reveres a "distorted" reinterpretation of the ancient faiths of the desert tribes, the only details of which we know is that a glorious death in battle guarantees your spirit ascends to St'oec, the highest of the 7 Heavens.
Bill King made mention of a "Prophet of the Law" taking over Araby and leading it on a xenocidal anti-Chaos crusade in one of his Gotrek & Felix book, being a clear pastiche of either Mohammed or the Ayatollah Kohmeni.
Brian Crag's "Zaragoz" describes Araby as worshipping a monotheistic faith they describe simply as "The One God".
The Two Crowns of Ras Karim, by Nathan Long, says that there are temples to genies and that the Araby make offerings to them for divine favor.
The Tomb Kings 6e armybook says that the Araby still practice some of the festivals and rites that originally celebrated Nehekhara's gods, particularly the death god Djaf.
Chaos cults are a thing; Sultan Jaffar was a powerful daemonologist, with Storm of Magic from 8e saying he had a pact with Kairos Fateweaver, whilst the 8e Daemons army book says that Araby's native magical colleges have been subtly manipulated/corrupted by a Lord of Change that possessed one mad mage named Mahik al'Rak.
In short: no, there's no modern canonical answer, it's one giant mess, and the fact that the original canon answer was literally "they're Islamic" is probably one of the things holding Araby back.