I mentioned the Templars invented the credit card a few days ago. I thought, for those who may be interested I'd explain exactly how it worked.
Calling a credit card may be a little misleading. It was actually more like a debit card. Pilgrims would make a deposit with a local templar, who would then code the amount onto a chit. At all the stops along the way... Inns... holy places... merchants of all forms... the Pilgrims could purchace or donate without cash. They would see the templars who would read their chit, make the relevant subtractions, and recode the chit. When the pilgrim returned home he would take his chit to the local templar who would read the final code, and if there was any money left over, it would be given in cash to the pilgrim. If the pilgrim had overspent, he would be billed.
Note that the Templars never charged interest. This was considered illegal for church bodies. Ursery it was called. The Templars got around this by instead charging service fees and rent.
See? Just a bunch of illiterate warriors.