One way to answer what is God is, is with an analogy that Atheists can understand. Science assumes; has faith, there is life on other planets, even though science has to no real tangible proof; seeing would be believing. If we accept their faith, for the sake of argument, it logically follows there may also be Aliens, that are millions of years ahead of us, in terms of civilization, culture and technology. If life took several billion years to form on earth, what is a few million years; head start or skipped steps.
We all die because the our body wears out and health problems appear. As we get older, the part of us, who we were; consciousness, seems to stay forever young. But we notice our body is not cooperating like it used to, as we age. We cannot burn the candle from both ends any longer. We have to watch what we eat and do.
Say the advanced Aliens, saw this organic body problem a million years ago. They decided to get rid of the fragile organic body and place consciousness into machines, that do no wear out and/or can be replaced as needed, in part or in whole. In other cases, they do not even use bodies at all, but rather only use energy fields; zero point energy, to sustain their consciousness, as they travel the universe at the speed of light
In their travels they come to earth. How would they need to present themselves for humans not to get anxious or paranoid? They are so far ahead of us, that the fear of novelty would kick humans into over drive. Being just consciousness, without any tangible body would spook many people; ghosts or astral projections. Science would be besides itself after all those years of denial. If they were in their advanced interactive machines, that are not harmed by bullets or bombs, the military would be very nervous. They would need to go slow, assess us, and try to dumb it down so humans can be comfortable enough to feel and want peace and what to learn about the future.
God has to be many things to many people. God cannot be himself; full strength, since he is way too advance and this would lead to fear due to ignorance. But if he dumbs down to something warm and fuzzy, we can understand or grasp, God has a bridge and toe in the door. This is why east and west religions have different ways to interact with God; different cultural needs, with each of these base religions, tailored to smaller and smaller needs, all the way to an individual relationship to a God variation. God cannot teach us things, if we are not ready to understand. Some are afraid to ask and others are not ready.
If you watch science fiction, not all scenarios are as effective in terms of audience appeal. Some things are easier to accept and others things are sort of expected, so we have an easy way to orientate ourselves. It is easier if the Alien has advanced tech bling. God is similar to that. We will find commonality. The main difference is, science fiction has more way to create sensory input into the brain, due to books, movies; audio visual and even toys. This can fool the animal brain since semi-hard sensory data will be collected and written to memory; extra false positive. Like magic, if you can see it, it is easier to believe.
Religion does not offer as much in the way of faux sensory input. Instead, it makes much more use of the imagination and our internal sensory systems, than our external sensory systems; more frontal lobe versus more visual cortex. The frontal lobe is more advanced in terms of place in evolution. God seems to reach us via the more advanced part of the brain. Science fiction dumbs it down more; sensory, since it characters are limited by the imagination; frontal lobe, of human writers, who then use actors, directors and producers to create sensory output; stimulate the imagination plus write to the animal brain.