First off the story in general, not that great pretty basic actually. However this is not my main problem with the anime. If a story is going to use a religion as a key point in their story they should at least learn the basic beliefs of said religion instead of making up nonsense. My point being a core belief in Christianity that EVERYONE can be forgiven and NOBODY is is too "unclean" to be loved by God. This next sentence may be slightly spoilery
The plot-line that a character decided that they were unforgivable and needed to atone with their life because they read a Bible is utter nonsense because the bible in fact says the exact opposite, kind of the point of the whole new testament in fact(maybe they had their mental break befor they got to that part lol).
anyway if your not religious you might not mind but it doesn't change that the creators didn't take even the minimum amount of effort to find out a little about something they talked about though quite a bit of their story.