And the soul that turneth after such as have familiar spirits, and after wizards, to go a whoring after them, I will even set my face against that soul, and will cut him off from among his people. (Leviticus 20:6)
The term “familiar spirits” is used in in the Bible to describe those who use information gained through spirits outside of God on a regular basis. In those days, these people would have included psychics, tarot card readers, palm readers, witch doctors, along with wizards. Is it harmless to get your palm read? Or to go to a tarot card reader?
According to this scripture, there is a stiff penalty: God turns His face from us. This means we will lose God's favor and His presence. If you were cut off from your people, you couldn't go to the temple to pray or to offer sacrifices: your prayers would have been hindered and still will be today!
Besides this direct reference, many Christians use the term "familiar spirit" to refer to a particular aspect of Satan’s network. We know Satan imitates God. Most are aware that we have a “guardian” angel assigned to us (Matthew 18:10, Hebrews 1:14). Sometimes Christians refer to the demons who have been assigned to us as “familiar spirits” because they know us and often have been passed down through our family line.
Many spirits can speak to us even those that are not from God:
But even if we or an angel from heaven should preach to you a gospel contrary to and different from that which we preached to you, let him be accursed… (Galatians 1:8)