I've heard that people validate miracles that have occurred because someone prayed to a dead person. This way they consider them as if they came from God, but unfortunately, giving more importance to the dead person than to God.
From Exodus we can read that Moses and Aaron performed a lot miracles before the Pharaoh and his magicians and sorcerers could also perform some of them, for example the conversion of the rod into a snake.
10 And Moses and Aaron went in unto Pharaoh, and they did so as the LORD had commanded: and Aaron cast down his rod before Pharaoh, and before his servants, and it became a serpent. 11 Then Pharaoh also called the wise men and the sorcerers: now the magicians of Egypt, they also did in like manner with their enchantments. 12 For they cast down every man his rod, and they became serpents: but Aaron's rod swallowed up their rods. Exodus 7:10 KJV
But the sorcerers weren't dead and the Pharaoh never prayed to them. Now, from the book of Revelation we read:
For they are the spirits of devils, working miracles, which go forth unto the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty. Revelation 16:14 KJV
So, Is it possible that demons perform unbelievable miracles, such us healing or resurrect dead people? Is such their authority that they could make a person to believe in a dead person or a false prophet instead of God?