When Rutherford claimed that the dead and ressurected C.T Russel was still communicating new light to him...that's called necrology. It's occultic.
Not true at all. In the book of Revelation, John was told by an angel that he was of his brethren, the prophets. He was told that twice. And Ezekiel calls the angel that ministered to him "a man." In all cases it suggests speaking to angels who once were men. Certainly, men can be sent back by God to communicate with them as angels. (I also don't believe angels are a separate class of beings as humans. An angel is simply someone who comes to someone on Earth with a message from God.)
In many near death experiences, relatives are sent with messages for loved ones. Many of these are accompanied by overwhelming feelings of peace and well being, which the Devil can't replicate in my view. In the case of Russell, he was supposed to be resurrected, but how did Rutherford know it was Russell? Evil spirits can mimic "angels of light" and deceive the living. One must have the proper keys of knowledge to detect deceitful spirits, and that must come by revelation. Otherwise, how would an ancient prophet like John know the difference. Twice he fell to his knees thinking he was worshiping Christ. Only did the angels reveal themselves.