What were the causes of the European Witch Hunt?
In order to unite everyone under Christianity, all other religions were demonized. Various aspects of pagan religions became associated with the devil. The pointed hat, once a symbol of wisdom, became one of heresy and evil. The image of the devil, that of a horned cloven-footed man, came from a depiction of a nature deity that the witches worshiped. Witch hysteria also became an economic enterprise, garnering the church considerable amounts of wealth and power.
The split between Catholic and Protestant Christians played a major role in the witch craze of the 15th century. The Reformation was a time of great religious upheaval and nobody felt like they could trust anybody. The hunts were more in central Europe and the borders of countries, places were there was less religious unity. A country like Italy or Spain, where there was a more spiritually unified population was less likely to have a witch hunt. Protestants were accusing Catholics, Catholics were accusing Protestants. Here’s an essay that discusses recent developments in the study of the European witch hunts. It’s rather long, but very informative: http://www.tangledmoon.org/witchhunt.