From the Bible Gateway:
People throughout history have sought to communicate with dead loved ones and to listen to their advice and experiences. But is it right to attend a séance or to seek a spiritist medium?
Consider what the Bible says;
Deuteronomy 18:10-12 teaches: “There shall not be found among you… a medium, or a spiritist, or one who calls up the dead. For all who do these things are an abomination to the Lord.”
God repeats His disapproval in many other passages (Leviticus 19:31; 20:6,27).
But didn’t King Saul consult a spiritist medium? Yes, he did. But remember that, at the time Saul did this, he was living in rebellion against God! In fact, Saul even disobeyed his own law, which forbade consulting mediums and spiritists (1 Samuel 28:3-19)!
1 Chronicles 10:13 says: “So Saul died for his unfaithfulness which he had committed against the Lord… and also because he consulted a medium for guidance.”
Finally, notice Luke 16:19-31. A rich man, who had died, wanted to give advice to his five brothers who were still alive. So he asked Abraham to send someone to his brothers from the dead;
“Abraham said to him, ‘They have Moses and the prophets; let them hear them.’ And he said, ‘No, father Abraham; but if one goes to them from the dead, they will repent.’ But he said to him, ‘If they do hear not Moses and the prophets, neither will they be persuaded though one rise from the dead.'”
This absolutely confirms that God does not approve of dead people coming back to speak to us! But it also shows that the reason God forbids such practices is simply this: God provides all the spiritual instruction we need in His word, the Bible! When people seek supernatural information from some other source, they show a lack of faith in God´s revealed word (2 Timothy 3:16.17)!