One way we can make sense of this by using a very old but functional definition of religion as simply the belief in nonhuman and supernatural intelligent beings that often descend from the sky. There are many definitions of religion, but this one is pretty standard.
There is another distinction about belief in nonhuman extraterrestrial intelligence, or UFO inhabitants, that makes it distinct from the types of religions with which we are most familiar. I’m a historian of Catholicism, for instance, and what I find when I interact with people in Catholic communities is that they have faith that Jesus walked on water and that the Virgin Mary apparitions were true.
But there’s something different about the UFO narrative. Here we have people who are actual scientists, like Ellen Stofan, the former chief scientist at NASA, who are willing to go on TV and basically make announcements like, “We are going to find extraterrestrial life.” Now, she’s not exactly talking about intelligent extraterrestrial life, but that’s not how many people interpret her.
She says we’re going to find life, we’re going to find habitable planets and things like that. So that gives this type of religiosity a far more powerful bite than the traditional religions, which are based on faith in things unseen and unprovable.