Deuteronomy 18:10-12

Let no one be found among you who sacrifices his son or daughter in the fire, who practices divination or sorcery, interprets omens, engages in witchcraft, or casts spells, or who is a medium or spiritist or who consults the dead.  Anyone who does these things is detestable to the Lord, and because of these detestable practices, the Lord your God will drive out those nations before you.

1 Chronicles 10:13-14 ESV

So Saul died for his breach of faith. He broke faith with the Lord in that he did not keep the command of the Lord, and also consulted a medium, seeking guidance. He did not seek guidance from the Lord. Therefore the Lord put him to death and turned the kingdom over to David the son of Jesse.

Gal 5:

19Now the works of the flesh are evident: sexual immorality, impurity, sensuality, 20idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, 21envy, drunkenness, orgies, and things like these. I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God.