Jesus opened up a new relationship with God to us. Something that was at the time hidden to the Jews. Christianity believes in a new age and a new relationship.
The OT vehemently condemns communicating with the dead, whether that be going through a divinator or praying to the dead yourself. The Jewish people knew better, they weren't ignorant of this. Jesus did NOT change what was condemned in Scripture.
Asking another person who is still alive on this earth to pray with you and for you is one thing, but asking a person who is no longer alive on this earth is
NOT ok
That isn't an example of asking the saints in heaven for their intercession. That's a whole different kettle of fish. Some sort of occult intervention?
Luke 16:17 - 31
He answered, ‘Then I beg you, father, send Lazarus to my family, for I have five brothers. Let him warn them, so that they will not also come to this place of torment.’ “
Abraham replied, ‘They have Moses and the Prophets; let them listen to them.’ “‘No, father Abraham,’ he said, ‘but if someone from the dead goes to them, they will repent.’ “He said to him, ‘If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.’”
In the above passages, the rich man who was no longer alive on earth. Was NOT able to intercede for his family who were still alive on earth. He was told that his family had Scripture to listen to and heed from. And neither was lazarus who also was no longer alive on earth able to do any sort of interceding, nor did he.
God set boundaries between those still living on earth and those who are no longer alive on earth. God set boundaries between humans and the spirit world. Jesus reinforced this in the above passages.
“Abraham replied, ‘They have Moses and the Prophets; let them listen to them.
What moses and the prophets had written down was sacred scripture. And this is what Jesus is alluding to, when He said "they have moses and the prophets. There is absolutely nothing in the OT or the NT that gives anyone permission to pray TO the dead. Neither is there permission to pray to spirits.
All that is written in Scripture, is all that God wanted us to know.