Some people have no intention of joining another faith, or, in some cases, the mainstream faith they split off of. Such people are called heretics, and the clergy of other faiths may get fustrated to the point where they simply kill the heretic, or the heretic decides to be a martyr. Either way, any of a player's units converted by enemy priests die rather than changing sides.
Researched at: Church
Cost: 200 Florins
Effect: Units converted by enemy priestly units are killed instead of converted.