Don't insult my intelligence. It still neither explain why the fal'Cie wish to call a deity, or why they think killing a shit-load of people will make one turn up. It explains nothing. It's a leap of logic that makes no sense. How do you make the jump from "hates the state of mindset the cocoon society" to "let's call God to change it". How can he justify his actions. Why would creating more chaos and killing everyone make God turn up, there's no justification for this assumption. Why would God "reboot" everything, there's no justification for this assumption. What fucking good is all this if you're dead? Never considered. How are you going to "talk to God" if you're already dead? Never explained....

This is not a case of me "no getting it", I understood the story in perfect clarity thank you, that's why I can see the many many ridiculous plot holes and massive amounts of circular logic. Trying to make me out to be an idiot who just doesn't get it isn't going to work, so stop it; the fact is the story is pants on head retarded and you're just too much of a fanboy to admit that.

would it help if there were some kind of reference to an old religious script in ff13, similar to bible, koran or other ancient teachings in our world, with concepts like the flood our judgement day to answer your questions?

Very big difference between "plot being handed to you on a silver platter" and "plot making sense".  Bioshock infinite is a great example of a story that leaves plenty of room for interpretation and symbolism while still telling a cohesive storyline.  Leaving room for interpretation doesn't mean "don't explain any of the rules or logic of your world to the viewer".  It means that you craft a strong and cohesive narrative and provide them with a solid foundation and understanding of your universe, its rules, and the characters within it, so they can use that to devise educated theories and interpretations of events within the context of that universe.

FFXIII doesn't do this.  FFXIII's plot is not open to interpretation, contains no interesting metaphor or symbolism, and requires no thought.  It simply is poorly told.  The writers just withhold information that is critical to understanding the plot.  It's not a matter of interpretation, it's a matter of lacking information and not clearly explaining things like what a Fal'cie or a L'cie is and giving little information about the backstory and mythology of the world.  The only way to actually comprehend the story is to dig through the game's encyclopedia which would be fine if this were a book, or if this information was woven into the gameplay as it was with Bioshock's audiotapes. 

Imagine if you were watching Star Wars, and they never explained what the force was, or if 1984 didn't describe the various ministries, new speak, or the thought police.  This is basically what Final Fantasy does.  They forego any sort of real exposition so instead of being able to engage, interpret, relate, or disect, you're stuck trying to piece together what is happening in the first place. 

Not especially no, it would be a flimsy reference that's hidden in a datalog (amongst the what must hundreds of datalogs), which makes no sense for the fal'Cie to put so much stock into, and would only serve to highlight how terrible the story is because it's never actually covered in gameplay, mentioned by the characters, or even hinted at by the world. It would be a perfect example of a total failure to grasp the concept of "show don't tell".

In short, I already know about the datalog, it's a vague poem that was presumably written by a human and has no backing behind it that would assign it any greater value than any other random peice of artistic expression. It's lazy grasping and even then it's so bady written I'd claim it doesn't qualify as an explaination. Hell they even hide it in the Analects which is the "unimportant fluff peices" section. Comparing that to the Bible or Koran is quite frankly insulting, and I'm an atheist, so that says something.

No-ones tastes can ever be wrong. Hell, if anything FFXIII should have an easy time convincing me as it works alongside my biases. I'm perfectly prepared to admit, honestly FFX is kinda crappy, for many of the same reasons the FFXIII is... however it does enough right that I'm willing to overlook it's shortcomings and really enjoy it. I've completed it at least 4 times now and when the HD collection gets here on Vita, I'll do it again. Hell, I'll probably play through FFX-2 again too (and that's really stretching).

The problem I have, is while I'm happy to admit that FFX is a 4/10 game that I enjoy despite it's flaws, I consider FFXIII a 2/10 game with little to redeem it, even to fans of the franchise, style, and genre... which includes me. Look at me, my all time favourite game is FFVIII; I'm the target audience for this game. If I don't like it, it's a failure.

Now, if you like it great. You've found joy in something that objectively isn't very good... and I'm happy for you. I enjoy terrible b-movies, me and two of my friends have regular pizza nights where we watch such things. Low production horror and 80's action. Films that are objectively bad, but we enjoy them in ways that are not the original intention of the creator and so find fun in something that should be considered awful by everyone.

Admitting that your tastes and biases change your ability to judge quality, and cause you to both underrate AND overrate things, and to make the effort to learn to assess objective quality seperately to your own subjective tastes is a sign of mental maturity. It shows that you're in control of your ego. It's a good thing to achieve.