can you explain Lazarus, dead four days in the grave?
Matthew 10:8
Heal the sick, cleanse the lepers, raise the dead, cast out demons. Freely you have received, freely give.
Matthew 11:5
The blind see and the lame walk; the lepers are cleansed and the deaf hear; the dead are raised up and the poor have the gospel preached to them.
Matthew 17:9
Now as they came down from the mountain, Jesus commanded them, saying, “Tell the vision to no one until the Son of Man is risen from the dead.”
also as for dead spirits and if they can talk and be perceived. look at Samuel raised up by a medium by King Saul (forbidden by God by the way)
1 Samuel 28:8-15
New King James Version (NKJV)
8 So Saul disguised himself and put on other clothes, and he went, and two men with him; and they came to the woman by night. And he said, “Please conduct a séance for me, and bring up for me the one I shall name to you.”
9 Then the woman said to him, “Look, you know what Saul has done, how he has cut off the mediums and the spiritists from the land. Why then do you lay a snare for my life, to cause me to die?”
10 And Saul swore to her by the LORD, saying, “As the LORD lives, no punishment shall come upon you for this thing.”
11 Then the woman said, “Whom shall I bring up for you?”
And he said, “Bring up Samuel for me.”
12 When the woman saw Samuel, she cried out with a loud voice. And the woman spoke to Saul, saying, “Why have you deceived me? For you are Saul!”
13 And the king said to her, “Do not be afraid. What did you see?”
And the woman said to Saul, “I saw a spirit[a] ascending out of the earth.”
14 So he said to her, “What is his form?”
And she said, “An old man is coming up, and he is covered with a mantle.” And Saul perceived that it was Samuel, and he stooped with his face to the ground and bowed down.
15 Now Samuel said to Saul, “Why have you disturbed me by bringing me up?”
And Saul answered, “I am deeply distressed; for the Philistines make war against me, and God has departed from me and does not answer me anymore, neither by prophets nor by dreams. Therefore I have called you, that you may reveal to me what I should do.”
now you have a Biblical example of the dead speaking.
Demonic practices are not said to not exist or not work, they are just harmful for the spiritual life of believers and are forbidden by God. Mainly because demons want to pervert and take control of God's creation and will eventually kill or drive crazy their worshipers. God tells us we can be slaves of righteous or slaves of Satan and sin.