Leviticus 20:6

And the soul that turneth after such as have familiar spirits, and after wizards, after men and women that consult with the spirits of the dead and use other forms of soothsaying, Leviticus 19:31, to go a-whoring after them, becoming unfaithful to the true God by such idolatrous practices. I will even set My face against that soul, and I will cut him off from among his people. Excommunication and death was to be his punishment for engaging in apostasy and for corrupting the people of the Lord.