I enjoy listening to score composers sampling Christian music as part of movie or television scores. ('course I like to listen to film scores anyway, but this is a nice bonus. {g} One of my favorite 'discoveries' along this line was the soundtrack to a fantasy strategy game years ago, _Fantasy General_: practically all of it involves variant arrangements of several Christian hymns.) In fact a moment ago, my Mac randomly brought up the main theme from the Batman: Animated Series; which, while not strictly anime (I suppose?) reminded me the topic might be interesting here, too.
So, to use BTAS as my example (okay look just pretend it's anime, okay?!--it's an illustration of principle), when Shirley Walker wrote the soundtrack for the first BTAS movie (Mask of the Phantasm), she revealed she was basing the main theme of the series (apart from occasional use early in the first season of Elfman's score from the Burton films) on what is fairly clearly an old Russian or Greek (or maybe Latin) hymn to Christ. I can't quite make out all the words, but Jesu is frequently obvious. (Further fun trivia note: Hans Zimmer was her assistant on the MotP score!! Dude moved up in the world subsequently, didn't he? {ggg!})
Sometimes of course the borrowing is more obvious ("Dies Irae" is prominently featured in which anime, for instance? No, I'm not thinking of non-discussion titles... {wry g}) But it might be less obvious, too.