Are aliens really demons, im confused?

Or is that just a religious belief? im not religious Im just curious and I like rrading other peoples theories. I have heard that the aliens are the ones that were cast out if heaven, the fallen ones, does that apply to all of them? The sons of god, does that make god evil then? Uf there demons why havent they,killed us yet, if there aliens why havent they shown themselfs? It makes me a little nervouse, because uf there intentions were good then the govt. wouldnt cover it up so heavily, and the fact that they will kill anyone that has evidenve and,is willing to publicly announce it is odd. So are we just doomed between different races of aliens or demons that wanting pick our heads off one by one? Is there any hope out there?