Briefly returning to stuff like African cannibalism and witchcraft, with a smidgen of Western devil-worship thrown in:
The way African witchcraft traditionally works is as an explanation for 'bad things happening'.
E.-E. Evans-Prichard's anthropological classic 'Magic, Oracles and Witchcraft among the Azande' has a nice little passage about 'witchcraft' vs. 'chance'. A hut has collapsed (eaten by termites) and the heavy roof has crushed a family. 'Aha! Witchcraft', say the Azande. 'No, no, it was an accident and a damn unlucky one', says Evans-Prichard. At which point the Azande want to know what the dickens he's talking about. It turns out Evans-Prichard can't sell the concept of 'bad luck' to the Africans for the simple reason that it makes no logical or narrative sense. ('You mean the hut fell down and killed these people for no reason at all? Pull the other one, will ya!')
The Africans know quite well why the hut collapsed in technical cause and affect terms (termites). What they want to know is why these people got killed this time, since huts fall down all the time with no bad effects. Their answer is 'witchcraft'. Things don't just happen without anybody's volition ascribing it to some weird power called 'accident' or 'bad luck' only makes sense if you've been raised to believe in them as Evans-Prichard realised.
So in order to make the world safe an working again the 'witch' has to be found, and witches usually cause bad things to happen without really knowing it or consciously wanting it. Thing is, when these things occur in Africa there are usually functional ways of exorcising the 'witch' and directing the anger that aren't really violent, and afterwards things can go back to normal.
That's the role of witch-trials they aknowledge that something bad has happened, that the world isn't random (which Westerners usually believe), that something can be done about a bad situation, and then normalcy returns.
Anthropologists usually find that this system works fine and that it's a symbolic way of identifying a problem in the community and then dealing with it.
Problems can arise (but usually don't) when you take individuals out of these societies and set them down in the West. Without the society surrounding and directing the belief in 'withches' into acceptable forms, you can get these violent incidents when a set of cultural codes and attitudes gone haywire.
If anybody looks into the situation of the people tourturing the 'witch' I'm 100% sure it will be found that they were in a very bad situation, deseprate and then resorting to a traditional way of dealing with problems that don't work since this time there is no surrounding society that can reassure them and help adress the real issues.
This is not to say they weren't responsible for their actions it's saying their culture didn't 'make then do it'. Culture (fishy concept) doesn't work like that.
Cannibalism:
Cannibals are fantastic to 'think with' in the words of Lévy-Strauss! That's way some scholars frankly disbelieve their existance. For instance William Arens, 'The Man-Eating Myth', a book from the 70's where this anthropologist went through whatever proof of cannibalism was around. His findings were so meager, he concluded that cannibals spring from the Western mind. Westerners are clearly obsessed with this idea.
That's prolly true, but Arens got a little carried away. In large parts of Africa there exists a huge and complex system of belief about cannibals. (Europeans are cannibals and blood drinkers for instance.) Cannibals are universally feared and hated. BUT, the belief system allows for an inversion of this dominant code. If cannibals are evil, they are also powerful, which means that a small number of people may actively decide to become powerful, dangerous and feared cannibals. That's the way Africans refer to them there aren't cannibal societies of cannibal cultures in their stories, just dangerous and bad individuals.
This concept of dominant code, sub-code and code inversion can be applied to (Christian) Western culture as well. Westerners don't usually worship the devil. Still, there are devil-worshippers around, behaving in ways that run counter to the dominant cultural code but in ways that ONLY make sense as an inversion of the attitudes and beliefs of the majority.
Does this make Western culture 'satanistic'? Hardly. Does a belief in cannibals and the odd beyond the pale African practitioner make African culture (Sub-Saharan, Central African stretching into west Africa) 'cannibalistic'? By the same criteria, nope.