I also had problems coming to the resolution I wanted from the Apostolic Palace...the so-called "Religious Victory". Playing as Isabella I founded Buddhism and spread it to my neighbour, Alexander. When I made contact with the other civs I also spread it to them, with Buddhism in at least one of the AI civs except Montezuma, who refused to allow me Open Borders and was running Theocracy. Later, Hannibal split off a colony in the form of Napoleon, but I was able to bribe him to convert to Buddhism so it must have spread to one of his cities naturally.
In the end, however, never did a resolution to vote me winner of the game ever arise, even though I am told this can happen. Eventually I discovered Mass Media and the AP was obsoleted. Still, I wonder why I never was able to pass that game-winning resolution. In fact, hardly any resolutions at all came forth throughout the entire game!