This comes from Erich Von Daniken’s Chariots of the Gods? - which had the “?” added much later - as well as Zechariah Sitchen’s works. They do purport to be nonfiction, but work as sci fi novels. Sitchin did not know Sumerian/cuneiform, and basically made up definitions and words that he claimed described alien space ships.

Graham Hancock and “Aliens meme guy” whose name I can’t be assed to spell haven’t really been using it as a religion, more just taking advantage of the History Channel.