Despite how pop culture depicts it, the Crusades were not purely religious in nature, there was a lot of politics in there. You didn't have all the Christians getting together and all the Muslims getting together. There were Christians with Muslim allies fighting Muslims with Christian allies and vice versa. Just because they were the same religion didn't mean they liked each other; heck, it was Christians who sacked Byzantium in the Fourth "Crusade", where very few Crusaders ever even reached Palestine.

What was the context of the request(s), if you don't mind me asking? (I had no luck with googling.) I've only read the parts that have to do with the First Crusade, which never mention this, so I'm pretty curious about it now.