The history of the RC church during the Renaissance is too complicated to deal with here. Suffice to say that power corrupt and absolute power, etc. There was too much power centralized in the Vatican, in Rome as a city, and in the Papacy as an institution. Check out Popes Alexander VI, Julian II, and some of the other "bad Popes." Check out the Synod where a dead Pope was unthroned, and the short reign of Celestine I (I think it was I).