I dont know how fiasable this is but it always seems that the problem for the Crusader States was manpower, the Teutonic States and Spain were both successfully Christianize because of immigration. So what if Urban instead of just offered indulgences for the pilgrimage, offered some sort of indulgence for living in the holy land. Put in some law that by living where Jesus lived, the sins were lessened(since he made up indulgences, he could make up something like that)
That would allow a fairly consistent stream of people moving to there, and they would most likely be a mix of all types of carriers, allowing a more stable society, a super religious one yes, but over a couple generations they would be more acclimated.
That would allow a fairly consistent stream of people moving to there, and they would most likely be a mix of all types of carriers, allowing a more stable society, a super religious one yes, but over a couple generations they would be more acclimated.