Some people also believe that we are in the End Times. Many people have bizarre beliefs about what is to occur. I've heard an interesting theory that the Antichrist will have to explain to all people remaining on Earth after the rapture what happened to everyone. That explanation will be that aliens took them. Aliens however will actually be demons, but the remaining people on Earth will be fearful as they realize the Bible is truth so they gladly take a ride from an alien. To their detriment. So, I have mixed feelings about aliens.
I don't have any real doubt that the better known aliens are at least in cahoots with satan.
I don't know about the assertion that the greys are bio-engineered robots encasing demons. Plausible, I suppose.
But, as with most of this stuff, it's extremely hard to sort out the disinformation from the flakey from the facts.