For buildings of the same name in other Tropico games, see Cathedral.
Cathedrals are welfare buildings in Tropico 3 and Tropico 4. Eventually, simple churches won't be enough to satisfy the need for faith that the island's citizens have and Religious citizens will begin demanding a bigger and more opulent cathedral. Cathedrals are necessary for presidentes to declare citizens "heretics."
Having too many cathedrals for an island's population is taken as a sign of Christian fundamentalism, which lowers relations with the Islamic Middle East.