Hmm... in all honesty I can't say much about that. If you're offended by cross-shaped items (like the Zohar), references to made-up "Gods" or calling something with immense power a "God," then this game probably isn't for you. The references to the Devil -- which is mainly the "666" mark on a certain character's hand -- don't really feel like references to religion at all (to me, at least). I can't say why the number 666 is on his hand since it would spoil some parts, but there are other people with numbers on their hands as well. Just think of them as a group, and he's the 666th member of that group. As for the "Hebrew" or "Greek" alphabet, it's really just things like the letters/words "Alpha," "Delta" and "Omega." For reference, .Hack and Sonic have even used the names/letters before. .Hack's server names and Sonic Adventure's 100-series robots, to be more specific.
Dark Cloud and Xenosaga are both $20, NYcKiD. They've been "Greatest Hits" for quite some time now. Dark Cloud 2 and Xenosaga Episode II are the ones that are still in the $30-$50 range.