POD: In the wake of the Morisco Revolts of 1568, some wise soul in the Hasburg Court pointed out that banishing the rebels to the lands of their enemies in North Africa was potentially a bad idea, Instead it would be better to deport them to the Spanish Crown's Burgundian lands, where they will be surrounded by Christian rivals and have no choice but to remain loyal/obedient to thier Spanish overlords. To that end, more than 75,000 were shipped and marched to settlements in the Franche-Comte and Spanish Netherlands by 1580.
By 1595, the guy who thought up that scheme died in disgrace, having narrowly escaped prison.
Entire villages in Franche-Comte fled into the Calvinist Jura, while many settled in an area of Geneva known as the 'Moorish Quarter.' Roughly half of them reverted to Islam openly, while the remaining crypto-Muslims saw the teachings of Jean Calvin as a bridge to the True Faith... or at least a less distasteful cloak for same.
The situation in Brabant and Flanders was even more inauspicious. After the gates to Antwerp were opened to the rebels by an alleged Morisco there were frightful attempts to cow the new settlers... which merely insured open flight and the formation of a regiment in return for the right to openly practice Islam. Others migrated more quietly into France where they blended in with the Heugenots(sp?) or across into Aachen and Juelisch-Kleve-Berg.
By the 17th century there were scattered communities of Muslims from Amsterdam to Geneva, growing both by natural reproduction and (due to the religious ferment of the Reformation) conversion. Many remained in thier own towns and villiages, but a full third established themselves in various cities as tradesmen. These communities were also the source of a disproportionate degree of theological scholarship both in Arabic and the local veranculars (the publication in 1610 of the bilingual Kuran Utrecht* in Nederlands and transliterated Arabic was largely seen as unprecedented... but soon proved far from unique). The writings of the physician Jozef Abensen on properly keeping the faith in a wholly infidel land such as the court of Copenhagen gained him a seat at Al-Azhar. The Thirty Years War found many 'Moorish' mercenaries fighting for the Protestant cause as well as missionaries quietly recruiting refugees, and it's end left penny packets throught the northern HRE both in monoreligious hamlets and major cities.
(*: The orthography for this tome, with only minor modifications, remains the most accepted romanization system for Arabic)
Long term ramifications?
HTG