An atheist doesn't have to believe in the non-existence of gods: nature takes care of that. An atheist only has to not believe in the supernatural (outside nature). As most believers think their god is both real and supernatural, they have to choose not to question their reality. Therein lies the evils of man: actions that are undertaken based on unquestioned beliefs.

If someone (atheist or theist) wants to believe in powerful aliens (power and technology are not supernatural), it doesn't require any dismissal of reality, but most religions do. They start by describing an alternate reality to children because children are natural believers of elders. Plain and simple; it's child exploitation for profit and power(prophets), and all behind a facade of mercy, love and morality that is usually more adhered to and examined by atheists than theists.