So I’ve already gone over Seymour and Yuna, and now I’m talking about Yevon. Yevon is the main faith in Final Fantasy X. Just about everyone follows it, and it makes sense that they would. Yevon’s teachings are the only thing providing the people of Spira hope, and it’s been the only thing providing that for the past thousand years. Sin keeps killing people and Yevon is their only way out. Summoners pray at temples run by Yevonites, which probably only enforces the belief that it is through following Yevon’s teachings that Sin will ever truly be destroyed. And when you have a world living in such terror, with their only escape being the church, it also makes sense that Yevon is the leading political power in Spira.
Yevon is actually a very interesting faith, and it is unfortunately not explored to the extent that I wish it would have been. It has a lot in common with Buddhism, Shintoism, and Catholicism. It requires a lot of disciplines for its followers—not using machina, which is what the people call machines—and some of its iconography is indicative of Buddhism. The temples and all the ritualistic practices are very similar to Shintoism, and as for the Catholic Church, it has a very similar hierarchy. Yevon is led by a Grand Maester (basically the Pope), and beneath him are three other Maesters (Cardinals). And then there are the people under them, so on and so forth.
People who don’t follow Yevon, like the Al Bhed, are frowned upon and considered heretics. Though the game does show people being killed for not following Yevon, it honestly surprises me that it doesn’t happen more, and it can even be argued that the Al Bhed who are killed are murdered for other reasons. The amount of scorn non-Yevonites face makes me surprised that executions based on faith, or lack thereof, are not common, especially considering that there are orders to kill Yuna after she is excommunicated.
But when a faith is established as the leading political power, while it’s not a big surprise that the leaders may be corrupt and while we can also argue that Yevon may have brainwashed the people of Spira, that doesn’t mean it can get away with some of the things it does. It doesn’t matter how corrupt an organization is, if it purposefully flaunts its hypocrisy people are going to notice every time. And that’s what happens in Final Fantasy X.