I think I can debunk a few theories here. I don't think obtaining the Templar's Guild has anything to do with being a good catholic or going on crusade.

I am playing a second campaign vh/vh as Scotland. The first one I was a good and pious citizen. This time I decided to be as aggressive as possible, basically forget politics and religion, and take every opportunity to seize territory and crush weakened opponents. I have destroyed England and Denmark. I am currently at war with 8 other factions, have no allies, have a papal standing of zero, where it has been most of the game. I have been excommunicated more times than I can count. I have inquisitors, heretics and witches crawling all over my territories. I have never participated in a crusade, in fact have used those opportunities to pillage pious nations that are silly enough to send their armies away to the please the Pope. I was offered a Templar's Guild in York after about 65 turns!