Yevon

In Final Fantasy X, the people of Spira follow the Teachings of Yevon. (Yevon and Yu Yevon refer to the same person) Yu Yevon was a summoner who lived in Zanarkand 1000 years before the start of the game. At that time there was a great war between Zanarkand and Bevelle. Zanarkand's summoners were no match for Bevelle's machina, so Zanarkand was doomed from the beginning. However, when Bevelle's troops reached the summit of Mt Gagazet, they heard a song echoing across the mountain. "Tis a song from an Otherworld" they said, and fled. At Yevon's order, many of the people of Zanarkand gave up their lives to become Fayths (people's souls trapped in statues whose dreams manipulate a phenomenon called pyreflies). Yu Yevon merges with the life-force (pyreflies) of the rest of the people to create an invincible armor called Sin. With Sin, he decimates Bevelle's army but also destroys Zanarkand in the process. He orders the Fayths to create a dream of Zanarkand as it was before its destruction.

Yevon's daughter, Lady Yunalesca, creates a technique called the Final Summoning to punish Bevelle and also to honor her father. A summoner who trains her aeon-summoning abilities can call the Final Aeon. The Aeon is created from a guardian of the summoner, who has a close bond with her; the guardian is killed and turned into a fayth, who then controls the aeon. Summoning the Final Aeon destroys Yevon's armor Sin, but Yevon then merges with the new aeon and Sin is reborn anew after a time. The summoner also cannot withstand the energy caused by this phenomenon, and dies as well. Yunalesca proclaims that this rite can defeat Sin for a time and give Spira hope for a short while, but unless the world embraces the teachings of Yu Yevon and atones for their sins, Sin will never disappear completely. Yunalesca uses her husband Zaon for the Final Summoning and dies, but refuses to be sent to the Farplane.



Bevelle is still terrified of Yevon and Sin, and in order to appease Yevon, St Bevelle begins to follow his teachings which Yunalesca brought to them. The teachings mainly revolve around the Final Summoning and the prohibition of machina, as it iis Yevon's wish that there will never again be a machina war. St Bevelle begins to set up temples throughout Spira, and in each temple is a Fayth. He also forms the Yevon Clergy, with four Maesters at the top, a High Priest for each temple, and many other priests and monks.

A Zanarkandian song which later becomes known as the Hymn of the Fayth is taken up by those who defy Bevelle, including the fayth inside the temples. At first Bevelle prohibits the use of the song, but after realizing that this isn't working, they instead spread a story about it being sung in defiance of Sin. Eventually it is adopted as a holy song by the Yevonites.