This is very interesting.
It almost seems that the witchcraft stories were made up of the same material as most urban legends. That is, they appeared possible given the societal presuppositions, and they became fixed against what later appeared as "commonsense". Also, some strange occurence, when re-told, might become a tall tale which was accepted among the folklore as certain proof that witches actually did exist, and had evil power at their beck and call.
Of course, some people could argue that this does not disprove the influence of the supernatural in the natural--but others, who have sub-consciously accepted the existence of witches as an integral part of their picture of the supernatural/natural interaction, would feel their worldview being destroyed.
One more thought--I agree and disagree with Scot about the story of the witch at Endor.
If I remember right, the references surrounding that story are to "spiritists" or "diviners" who communicate with the spirit of a dead person, not to people who actually raise the dead.
It reads more like a ghost-story than a back-from-the-dead story. It also appears that whatever necromancy (or trickery) the woman usually practiced, something else happened--and she was surprised.
Given the context of Hebrew scripture, it is hard to conclude that resurrection from the dead was being talked about in that story. The Hebrew scriptures do tell of two resurrections that I can remember (both events were connected to Elisha, if I remember rightly). Whether or not you accept those stories as historical, it is hard to accept that the event at Endor involved any claim of resurrection from the dead.
However, I agree with Scot--that story is the only Scriptural reference to anything akin to witchcraft, as he was referring to.
And it is pretty weak, as a story of a person sellling themselves to an evil power. It looks more like a person selling their abilities, whether fabricated or real, to other people.
Doubting witchcraft seems to have been happening through Europe then: Montaigne at about the same time said that of witch trials that we rated our hypotheses pretty highly if we roasted people alive for them.