My random topic generator happened to spit out two "why are they scary" topics in a row. Yesterday, I tackled ghosts. Today, witches.
I've talked a lot about the Other in here and how we fear things that are different. Witches represent one of the oldest fears we've had since civilization, the other religion. People who don't practice the same rites and rituals as we do can scare and confuse us. Just look at how Christians view Muslims and vice versa. There is modern witchcraft, of course, which takes its cues from nature and is peaceful...that is not the witchcraft people get scared of. Somewhere along the lines, those who practice Satanism and the dark arts became labelled as witches and warlocks. These worshipers of alternate gods represent the dark underside of what people see as organized religion.
Sort of like vampires, a witch can seduce people away from the life they are supposed to be leading. They can change form and cast illusions to confound and confuse people. Even the satanic witches are still bound to nature a bit with their familiars (like black cats or, in the movie The Witch, a fluffy bunny). Traditionally, the ingredients for their brews are a grocery list of disgusting things found in nature that no one wants to deal with. If there is a blessed natural world, there must be a cursed one, too, and witches are from there. Therefore, they must lie and flatter to bring people over to their side. Who would go willingly?
In reality, not so many witches have really existed as there have been people who are viewed as different and are persecuted as witches. Take the Salem Witch Trials, rebellious children were able to indict their fellow townsfolk on scant or non-existent evidence. The proscribed methods of determining guilt usually involved dying as a Christian or dying as a Witch but dying either way. And like the Inquisition, you either confessed your sin or you were hiding it but you were guilty no matter what.
As religion seems to loosen its grip on the zeitgeist, as it has since the industrial revolution, witches have lost their power to scare as much as well. Perhaps they will make a resurgence as representatives of the natural world we have lost touch with but that barely seems as scary as the devil's minion turning you into soup.