Adding a surrender mechanism to all European‘s priests and Aztecs warriors‘s priests North american civ’s healer and Asian fighting monks

Age of Empires III: DE III - Discussion
7

Priests and church

If none of this is done, just limit the priests to 5 (actually 30). They will stop costing population.

Their purpose could simply be to make the town center trigger, while they are unoccupied, since they can be garrisoned in the town center.