Ok, I forgot about the judical system corruption. And yet, cathedrals do have a positive effect on reducing corruption, see the USSR experiment on live without moral focus points.
But let's say your premise is partically correct, there is some corruption in cathedrals, Roman, Greek Orthrodox, or whatever, what type of corruption is that? Isn't it more a corruption of happiness than a corruption of production or gold? Except in countries where cathedrals are converted from religious institutions into political institutions supported by taxes instead of by donations, I have not seen cathedrals siphoning off 5-20% of local work effect {production/shields}, or of gross income {gold}, or of food, or of science activity {beakers}.
But you do raise an interesting idea, happiness corruption. Huh, the father a cathedral is from the palace, the less happiness it produces. Sounds like a legitimate RFE for firaxis. Now extend that idea to the sistine chapel. Rather than doubling happiness in all cities on continent, change to a ranged effect, 3x in city of sistine, but scale down to 1 extra in remote cities, based on distance from sistine chapel.
Man if firaxis impliments just a few of the ideas we post on these forums, we offer perpetual employment for their programmers.
Happiness corruption-- What do others think, would this enhance or detract from game?