Not all NPC sororities are founded on Christian beliefs. Mine is, but not every one is.
Also, religion was not really much of a part of my chapter at all. I think where the founding roots come out is in ritual, but not in any way that should make anyone of any religion uncomfortable.
I do think that in the bigger picture, NPC sororities are designed for any woman of any background to be a part of and find sisterhood and friendship. However I'm not naive enough to think that the climate of every campus makes it that way, especially in the south.
One thing I do get sick of though, in general, is people being forgiving of racism and discrimination because "it's the south". I am in NO way saying that all southerners and all southern campus are like this. But i've heard this kind of thing in many different forums. And it just kind of annoys me.