Christianity dislikes Witches/pagans and Wiccans because they don't worship what they consider to be the one true god; among many other reasons.
Chanting can be a form of incantation but not necessarily so. Why does who approve?
Fact - Witches are not evil. Witches can work spells to heal, to help, to curse and even kill. There are times when all of these are called for. Remember, a doctor can kill too, doesn't make him/her evil. And really, what is evil?