Mediaeval Catholic church please. No other church sold indulgences (the other major church, Eastern Orthodox, definitely did not). Yeah, I'm a semantic nazi.
PS: great comparison, I'll steal it for my own arguments. With your permission of course.
Not my comparison, so go ahead. The PDF I linked to was interesting because I'd always wondered if carbon trading (in all its forms) helped much, and the answer seems to be "no".
PS: great comparison, I'll steal it for my own arguments. With your permission of course.