In Deuteronomy 18, Moses repeats the prohibition against going to mediums... “for these nations, which you are about to dispossess, listen to fortune-tellers and to diviners. But as for you, the LORD your God has not allowed you to do this.” (Deuteronomy 18:14) Moses immediately proceeds to say:
The LORD your God will raise up for you a prophet like me from among you, from your brothers—it is to him you shall listen (Deuteronomy 18:15)
God spoke to His people through prophets; specific men whom God raised up to be His voice to the people. God says in verse 18 “I will put my words in his mouth, and he shall speak to them all that I command him.” Prophets spoke on behalf of God, and it was the prophets who wrote Scripture. Deuteronomy 18 also speaks about carefully discerning whether a man who claimed to be a prophet was legitimately a prophet. God wants us to listen to Him. Are the dead wiser than God? Are the dead more trustworthy than God? Even when king Saul used a medium to speak to Samuel the prophet from beyond the grave, his actions were condemned. If it was wrong to speak to a former prophet through a medium, how much more if we try to contact anyone else?
In the New Testament we read:
Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. (Hebrews 1:1-2)
And the Apostle Paul says that the Church is “built on the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone” (Ephesians 2:20). The point is that those prophets; the only ones we are to listen to according to Deuteronomy 18 – they wrote down the words of God for us and we have them in the Scriptures. Where Deuteronomy commands us to listen to the prophets, it commands us to listen to the Scriptures which are the words of the prophets, which are the words of God. “But” (Hebrews 1 says) “in these last days God has spoken to us by his Son.” We no longer have prophets because the “final word” has come to us; Jesus Christ, the “cornerstone”. When we want direction in life, we don't turn to the dead; we turn to God, and to God's word in the pages of Scripture.
Now some might say, “I don't want direction from my deceased relative or friend... I just want to say 'Hello' because I miss them.” This is understandable – death separates loved ones, and it's tragic and sad. God doesn't want people separated in this way. Our longing is to be reunited with our loved ones some day. But we must bear this sorrow and grief in the present, because this is the consequence of our sin. Rather than go around God to be reunited in some partial manner now, we need to trust and follow Christ with the confidence that He will reunite us in the day of our resurrection. And if that loved one is not saved, then we experience the hopelessness of sin and are driven all the more toward our Saviour, and to the ministry of sharing the message of Christ's salvation to the world.
And when they say to you, “Inquire of the mediums and the necromancers who chirp and mutter,” should not a people inquire of their God? Should they inquire of the dead on behalf of the living?