The whole "a spell is evil" thing is really a bad concept, as only the intent can be evil or a part of casting the spell requires an actual evil act, like a sacrifice or a certain spell component. I get why there are good/evil descriptors in the game, but they should never affect alignment imho. If you cast infernal healing on a dying child, is it an evil act? Do it again for his also dying parents and your soul is doomed.