I wrote a thing on this for the 25th Anniversary magazine. I was mostly pointing out the allusions and comparisons between the Catholic Church and Yevon, but I think it gives an interesting framework. Game Theorists on YouTube did a video critiquing whether or not FF was anti-Religion. I don't think it is; many JRPGs use religion as villainous entities but it's not necessarily a commentary on our institutionalised religions. I do think it's an interesting way to present a critique, though: parts of different religions can be examined under a new lens which allows us slightly more objective insight (accounting for all the biases in creation and critiques, of course). I think Wakka is an excellent vehicle teaching us that we shouldn't uncritically believe everything we're told. Like Fynn, that's about all I'll say on the topic before I repeat myself extensively