ETs could communicate without radio, quite conceivably, and do things that we could not tell from magic. Their assurances that what they were doing was based on advanced technology and science would simply have to be trusted; there would be no way to verify it.
We cannot even verify by our own investigations that NASA has sent vehicles into space to visit other planets; we just have to trust them. But even if they have, what does it mean? They have not yet said they have found any kind of life, but what about when they say they have found an advanced civilization that is communicating with them?
How would this be different from those who say they are communicating with ghosts, Bigfoot, aliens, and departed loved ones here on earth? There are different kinds of electronic devices that are made to aid ghost hunters, like the “spirit box.” The mythology is similar.
There is no evidence whatever of any more advanced civilization anywhere in the universe. This is a modern mythology, or a belief system based on assuming billions of years of evolution, in which other planets could exist that have had more time to evolve and are far ahead of us technologically.
We reject what we are told about intelligences in the cosmos. We are set up for a takeover by paranormal entities because of our gullibility to materialist mythology, and our rejection of the revelation of God in the Bible, and the information He provides about the entities that do not have the best interests of humanity at heart.