It isn't that strange organized religion tends to turn ugly, they're essentially dictatorships with only a few exceptions, with no way to fire any of the high ranking clergy. Sure, the pope or whatever, might be benevolent for a generation or two, as well as the organisation under them. But then a rotten egg is installed, and the rest experiences corruption creep. Like, if we take an example from state level, Nero in Rome. And after that the status quo will be that much harder to change...
Tell me one major religion this all hasn't happened. There isn't one...