I did a report on the history of witches as my final project for my religious studies, and I learned some very interesting things.
If you go back before the big Christian witch hunts you'll see a lot of reports of people getting burned for accusing others of being witches. The explanation was because the church believed that only through God could you perform "magic" so even if someone tried to cast spells and what not it would be ineffective. Therefore the belief that others could perform magic was seen as just as pagan as people attempting it.
So if you accused someone of being a witch there was no grantee the "witch" would get killed, but you sure as hell would just for thinking witches existed.
As we all know the church eventually gave in to the people's demand for "justice" and the big witch hunts started.