Personally I think they are just deluding themselves, but if they aren't then laws about witchcraft aren't unreasonable.
Schools need to revise their teachings on the Salem witch trials. If there really are witches today there must have been witches back in 1692 too.
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The most brutal witch hunt in English history was triggered in the shire of Essex in 1645 by witchfinders Matthew Hopkins and John Stearne resulting in scores of grisly executions. The tale is well told by Malcolm Gaskill in Witchfinders: A Seventeenth Century English Tragedy.