I think this is the wrong forum for it; this will probably be moved to Philosophy/Politics/Religion.
Anyway, I don't think this is violating anything. The songs are probably sung because they are art, as is the literature, and that is why they're appreciated. Go too far with the whole seperation of church and state yarn, and you'll end up trying to strip any and all mentions of religion from the public sphere. This is not only ridiculous, it's impossible.
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"And lo, the beast looked upon the face of beauty. And beauty stayed his hand. And from that day on, he was as one dead."