"Sin kills anyone," Tidus corrected. "There was this religion called Yevon that claimed that people could atone for their ancestors' wicked ways if they didn't use the forbidden machina"--his voice was dripping with disdain as he said the words, complete with airquotes--"but it was all a bunch of bull. People still believed it, which is why they would get upset that they died if they had followed Yevon's teachings."
He leaned back on his palms. "People tried. The only way they knew how to for a long time was through the Final Summoning. Someone a summoner loved would sacrifice themselves, and it was said that, if the bond were strong enough, the summoner could defeat Sin with the Final Aeon. But, we discovered that the Final Aeon then became Sin, so it was this endless cycle." Tidus offered a lopsided smirk. "We did end up killing him, though."