I'm reading A Concise History of Spain by William D. Phillips Jr. and Carla Rahn Phillips (2nd edition), and when talking about the conquest, conversion and assimilation of al-Andalus they state the following:
The converts from Christianity to Islam came from two quite different categories. At the top were members of the Visigothic royal house, high nobles, and influential families [...], who saw political advantages in joining with the new rulers. But members of the local elite were few in number. Far more numerous were the lowly Visigothic or Hispano-Roman Christians who converted to Islam. They typically occupied low positions in the social hierarchy. (emphasis mine)
Nothing more is said on the motivation these last two groups could have had for their decisions. So why didn't the local elite follow the example of their higher ranking countrymen? And on the other hand, what advantages did the lower classes get from conversion that the local nobility didn't get, or chose to forgo?
I'd suggest you start with this post of mine, and the followups in that chain. And then read this post I also made. They both relate to what you're asking about here. If you have any followups after that, I'd be glad to field them.
It's difficult to observe significant conversions during the VIIIth century, but it's true Latin sources are rare in this period and doesn't really focus on the phenomenon.Geographic factors might have prevailed into how quickly conversions happened : Toletum seem to harbour a Christian elite still into the Xth century (both due to its prestigious past and links with independent Chistian principalities in the North); but the Sarq al-Andalus (roughly, the Levante) seems to have been rather quickly Islamized (due to a stronger Arabic presence and political dominance and Berber presence) maybe entirely so at the end of the VIIIth century.It took more or less time for conversions to have a social impact, and not all Gothic aristocrats (what remained of it, at least) might have acted similarily.There's no particular reason to not consider Banu Qasi' conversion not taking place in the VIIIth century, and urban muladi dynasties, especially in the South and East, either. On the other hand, there's no strong evidence this was necessarily the rule : Theodomir/Tudmir submitted to Arabo-Berbers up to going to Damascus to acknowledge the Caliph's authority but his son kept a Christian name which would point to a non-conversion. Similarly, the powerful Gothic nobility in Gothia/Septimania simply didn't seem to have converted.
The reasons for conversion there should be looked over a power logic : where Arab nobility (politically dominant even if they were but a small minority compared to Berbers) was present locally and took over lands, assets and politics; the better way to preserve familial power was to integrate oneself to them. Not that conversion made Gothic families equals, but it allowed them to partake in local power more efficiently and critically to make piece to a sense of social status insecurity in the establishment of a new state whom their relation (which was central to their position in the Gothic realm) was challenged.When Arab presence was much less observable, in peripheries or enclaves, there was a lesser motivation to do so quickly.
The permanence of a Christian local elite could be explained trough the lack of an important Arab population and the need to rely on Christian service until the purge decided by Muhammad I in 852.Basically, petty and middle nobility kept the same role they had before, without a real necessity to change religion for most of them, conversion on this regard being more tied to Islamic prestige, patron/client relationship, etc. from the IXth century onward; which tended to be seen with suspicion by Arab in time of crisis, as possible "false conversions".But the matter of Christian identity remained strong (the Gothic realm being remembered as a beacon of religion) and the "Martyrs of Cordoba", a series of monks (whom at least a part came from the service nobility) being killed to publicly engage an anti-Islamic discourse, actively searching martyrdom for professing their faith as such : as such, it could be seen as a reaction against the growing Arabization of Christian communities in al-Andalus.
As for the lower classes...
The urban and rural lower classes tend to escape from the net of available historical evidence as easily in the Umayyad as in the Visigothic period(Early Medieval Spain; Roger Collins)
It's worth mentioning the migrations that took place in the VIIIth and IXth century to northern regions : Cantabrian highlands and Carolingian-held Spanish March (which roughly included both Catalonia and most of Languedoc) where they are called Hispani. It's next to impossible to prove that it had an aristocratic component; and it might be rather a way to "vote with one's feet" when it came to accept or not the subordination Christians find themselves into in Spain (the letter from Louis to the Christians of Merida actively proposes them to move into his lands), especially from local elite.
-A propos de quelques Hispani; Xavier Gillard, Philippe Sénac; 2004
- Early Medieval Spain; Roger Collins; 1995
- Les Mozarabes; Cyrille Aillet; 2010