Witchcraft has been seen re-occuring throughout history all over the world. But at what point did it go from being innocent herbs and spells to heresy worth of being burned alive?
Cunningfolk were always seen as the communities healers, who could use their herbs and simple magic to help cure someone of an illness. In the beginning, it was all completely innocent and really not a big deal. During the Conversion Phase, even countermagic wasn't seen as being inconsistent wth Catholicism. It really wasn't taken seriously and was believed to be easily undone. Witchcraft was practiced commonly. But through the 15th and 16th centuries, witchcraft slowly evolved to a crime punishable by death. The crime vs. punishment escalted quickly when when it become recgonized as "crimen exceptum" - a crime against not only man, but God as well.
Personally, I feel that as the Roman Catholic Church grew in influence and importance around Europe, they felt threatened by people believing anything besides what the Church thought. Hundreds of years ago, with the lack of knowledge we now have, almost everything was a threat to humanity. Another contributing factor was the beginning's of the scientific revolution. At this time, people began to divide magic in to "high" and "low" or "black" and "white." High or white magic was used by the elite - typically men - and was a typically seen as a positive thing. This type of magic included alchemy and astrology. Basically, any kind of magic that was a skill and you had to be trained. Low magic, was harmful and simple - usually practiced by women. This division made witchcraft go from demonic association of with paganism to demonic association with heresy.
In early Christianity, people thought that witchcraft was an example of "Satan transforming himself into an angel of light" and fooling people to do demonic work. It seems that the Catholic church was against witchcraft predominately because it distracted from God and the Church. They did not want people looking for answers for anything, anywhere besides the Church.
By the Late Middle Ages, the Church saw all magic as black and thought all witches were part of an organized and demonic cult. It was assumed that all witches had taken part in a ritual pact with the Devil and in Sabbath regularly. With it now being seen as heresy, this is when the prosecutions started becoming more and more frequent. Since it was seen as an organized crime, all punishments were severe, usually leading to death or torture at the least. At this time, anyone was capable of being a witch, so paranoia only grew as time went on.
So how did witchcraft go from being a casual practice of divination or spells to an unbreakable pact with Devil? Were witches really taking part in Sabbath's or was it exaggerating out of fear? It seems the most likely answer is probably a little bit of both.
Do I think that witches were actually eating babies and having conversations with the Devil? No, highly unlikely. But at the same time, I do believe witchcraft was a common practice that spread quickly and some probably took it further than others.