Whenever I read about the crusades you hear a lot of nonsense about Christians thinking Muslims were polytheists, worshiped Muhammad as a god, etc. But given the centuries of continued peaceful contact between the two in Andalusia, shouldn't some accurate knowledge have filtered to Church leadership? Or were they just not interested?
EDIT: Obviously I'm talking about scholars and politicians here, not illiterates.
Sorry for the late response, I missed this one when it was posted! I was just answering a similar question about depictions of Muhammad and Ali in Dante and I linked to some previous answers of mine that I can paste here as well, hopefully they're helpful:
I'm a Crusader heading towards the Holy Land in 1096. How much do I understand about Islam?
William of Tyre's understanding of Islam
Why and when did Westerners stop to refer Muslims as Mohammedans?
Basically, even if there was some cultural contact in Spain (and Sicily), there wasn't really a ton of it since both sides pretty much segregated themselves from the other side. Nobody knew much about Islam because they just didn't care to find out. It wasn't until after the crusades began, in the 12th and 13th centuries, that anyone significant really wondered what Islam was all about.
Medieval Muslims had the same problem though, they didn't know or care about the different kinds of Christians and the specific doctrines of Christianity:
Did medieval Muslims understand the division between Latin and Greek churches?
What stereotypes or preconceptions did the Arab world hold about Europeans during the Medieval era?