If the following happened:
(1) A being appeared out of thin air in the middle of some live televised public event. Appearing halfway between home base and the pitcher’s mound in the middle of a world series game would be a good way to do it
(2) This being displayed supernatural powers (many possibilities discussed already upthread)
(3) This being was incredibly charismatic. People were drawn to this being, and reported great happiness at being around this being. Everyone liked it. It was funny and kind and caring. But people who had been exposed to this being did not (at least apparently) become mind-controlled robots… debate would still rage, even among those who had been directly exposed to this being’s Apparent Radiant Goodness as to the exact nature of this being
(4) After hearing many people I trusted claim that praying to this being would result in prayers being answered, I prayed to this being, and was answered. That is, I assumed a “prayer-ish” mindset, and then felt that I was communicating with another being… and clear two-way communicating took place. I kind of envision the being as being like some kind of super-therapist… not removing free will by telling me what to do at every moment, and in fact refusing to do so, but rephrasing situations and pointing things out that clarified my own thoughts on the topic, and how I could use my own capabilities and tendencies (which the being knew better than I) to solve these issues
(5) When asked who the being was and why it had only now appeared, it claimed to be God, and showed people (via magic) the creation of the universe, and explained why it had only now appeared.
(6) (here’s the key point) All of the above MADE THE WORLD AND MY LIFE BETTER. The advice that this being gave caused the people of the world to love one another at least somewhat more. The influence of this being was clearly benevolent… and I don’t mean into some kind of theocratic god-worshiping world of clones who do nothing but sing hymns morning and night. I mean, the world was actually better… people were happier, crime was down, disease was down, etc. More people were good and fewer people were evil and there was more happiness and more productive fulfillment of the potential for human greatness.
Basically, I want Aslan to come back 
If all of the above happened and continued for long enough that I was certain I wasn’t dreaming, I see no reason why it would be more logical to define that being as either hallucination or super-advanced-alien than “God”.