Once you understand that, I guess you object to talking to the dead, eh? Jesus talked to Moses and Elijah at His Transfiguration. Now Elijah was taken alive into heaven, so I guess he was (and is) still alive (even according to you--I know on the basis of Holy Tradition that he is). But Moses died. Thus Christ Himself provides and example of speaking to the dead, and are we not to imitate Christ in all things?
The were sent to Him of God. And God followed thereafter in a Cloud. That was God's Doing and it was to serve a purpose. Wow, never thought of that did we. The Lord sent them back to earth to speak to Him. And God the Father was in charge of this communication, not men trying to communicate after their own fashion. Communication with the spirit world is restricted to what God allows us to see. It's the reason that speaking to the dead is against God's law. I've said that before. This is nothing new. The appearance of Moses and Elias was the doing of God within His law. You trying to contact dead people is violation of the law.