Well, holy chorae fit into the worldbuilding very well.
God finds sorcery anathema - so schoolmen are damned.
Chorae's sole purpose is to undo the wrongs wrought from sorcery. They do gods work - therefore holy.
I noticed in a previous post, you didn't say God. Rather, the diety the has most power on the Outside. See, I get very confused when talking about the God vs the 100. I recognize the difference, the 100 are shards of the God, principles you might say.
But, when Kellhus explains the God to Proyas, I am assuming he is talking about the 100. Because, even when Kellhus talks to whoever in his dreams under the tree, whoever says that he is trying to drive the God forth. I guess in order to war with him. So, it's all rather confusing to me.
ETA: it's probably Kellhus who is under that tree, just his version of himself in the Outside. But, I always hold out hope it might be Moe.