King Manasseh was one of ungodliest kings to ever rule over God's people. The biblical record of his wickedness includes explicit statements that show that he was profoundly involved in the occult:
2 Chronicles 33:6 And he caused his children to pass through the fire in the valley of the son of Hinnom: also he observed times, and used enchantments, and used witchcraft, and dealt with a familiar spirit, and with wizards: he wrought much evil in the sight of the LORD, to provoke him to anger.
He was so wicked that he even made God's people to err and do worse than the heathen:
2 Chronicles 33:9 So Manasseh made Judah and the inhabitants of Jerusalem to err, and to do worse than the heathen, whom the LORD had destroyed before the children of Israel.
In spite of his great wickedness, God graciously saved him when he repented under the fierce judgment of God on him:
2 Chronicles 33:11 Wherefore the LORD brought upon them the captains of the host of the king of Assyria, which took Manasseh among the thorns, and bound him with fetters, and carried him to Babylon. 12 And when he was in affliction, he besought the LORD his God, and humbled himself greatly before the God of his fathers, 13 And prayed unto him: and he was intreated of him, and heard his supplication, and brought him again to Jerusalem into his kingdom. Then Manasseh knew that the LORD he was God.
Careful consideration of the biblical revelation about him instructs us about two key points that many may never have understood.