In the Middle Ages witchcraft was feared thoughtout Europe, people thought that magic was an illusion created by the devil and was associated with worship of the devil. Some say that their are different types of magic, Black magic and White magic. Black magic was more associated with the devil and had santanic symbols. People thought that witches could cause harm to society by causing accidents, bad luck, illnesses and death. Witches got the blame so if someone fell ill for some unknown cause then witches got the blame for it. White magic had Christian symbolism that had more to do with nature and herbs, White magic was believed to be used in spells such as love, health,goodluck & wealth. Astrology and alcherly which is about potions such as turning metal into Gold and searching for a cure for a deadly illness are considered to be Abe apart of magic.
In the Middle Ages, there were some people who believed in witchcraft, which is not any different than today. What was different was that in the Middle Ages, there were laws about it. Early on, there were all sorts of laws, some of which outlawed witchcraft. Other, very important laws, such as the legal code of the Carolingian Empire, made it illegal to believe in witchcraft because it was a superstition. The the logical conclusion was that executing a witch was murder based on superstition and a capital crime.
As the Middle Ages progressed, ignorant people called on the Church to do something about witchcraft. In time, the Church responded with bulls against the practice. In the late 13th century, when the Renaissance was just starting to begin, and after about 800 years of the Middle Ages were over, there began inquisitions on the subject, with some very uneven application of laws. Some people were prosecuted, but there was no clear understanding of what should be done with them. Some were admonished not to be bad and released. Others said confessions and were told to repent. A few were punished, and a very few punished with death.
After the Middle Ages were all over and gone, people recorded histories about how unenlightened medieval people were, and calling their own period the Renaissance, a rebirth of the high culture of ancient Rome. It was during this age that the Church had professional witch haters write books on how to discover witches. These books were produced on the newly invented printing presses, and used by enthusiastic persecutors of ignorant people. Thousands of people were tortured and executed. Among the most important culprits was King James I of England, who wrote books on the subject and instituted actions against witchcraft, 150 years after the Middle Ages had ended.
Later, historians believed that the Renaissance people were more rational than people of the Middle Ages, possibly because they believed what Renaissance people said about their own greatness. Personally, I think a lot of it was because the Renaissance had linear perspective which meant paintings were much more realistic than medieval art, and this vision was thought applicable to the rest of comparisons of the two times. However it happened, the Middle Ages came to be defined in most people's minds as a time of ignorance, and the Renaissance as a time of rational thinking, so irrational acts were regarded as medieval, regardless of when they were committed, and science was always ascribed to the Renaissance without thought to when it developed.
There is a link below to an article on witch hunts.