I don't need to take magic mushrooms or other psychedelics to know this. Unlike many atheists, I do not call myself a humanist; I do not believe humans are innately superior to other animals, and do not believe we are necessarily the most intelligent life in the universe. We are still a very ignorant species, with much to learn about the world.
However, just because there might be other more intelligent life forms out there—or even among us, hidden to our senses—doesn't mean that I would call these beings god/desses or worship them as such. And the idea of God as a sole, omnipotent creator deity that takes an active interest in human affairs—an idea I thoroughly reject —is pretty specific to Western religion. I became an atheist as soon as I realized that God was made in the image of man, rather than the other way around.
We can marvel in the wonders and mysteries of the universe without needing to believe in or worship any deities. We can be kind and avoid harming each other without needing God to tell us this is the right thing to do. As it says in the Wiccan rede: "An' it harm none, do as ye will."