The pope screwed me over the other day. Was leading in points during a crusade for the kingdom of Jerulsalem and my stack was taking down a territory next to a combined english and papal stack that was taking down another. Then a big muslim stack arrived and attacked the combined english and papal force. They were going to lose handily, but I wouldn't be able to handle them either, so I immediately marched my troops to join the fight.
They were able to turn the tide.
Unfortunately though, since it was the English troops who were initially involved in the battle, they got all the credit for the victory. This gave them *just* enough points to take the lead on the crusade chart. Muslims surrender, and bastard pope gives the kingdom of jerulsalem to the king of England.