Why were supernatural elements in a play more freighting for audiences during Shakespeare time?

During Shakeaspeare time, people actually believed in witches and demons. They were extremely superstitious, and mystical/supernatural beliefs affected their everyday lives. If someone was ill, it was not uncommon to believe that person was cursed, for example. So seeing the supernatural being represented on a stage was especially frightening, which is also why magic and the supernatural are a recurring theme in Shakespeare plays.