Signs is a masterpiece and can be enjoyed if one simply interprets the film as described above. However, there is an alternative way of looking at the movie. For it can be argued that the creatures that come to earth are not aliens from another planet…but demons from Hell.
One clue to this other meaning is the seeming absurdity of the central plot element: The aliens, who possess such advanced technology that they are able to travel across galaxies, are yet incapable of breaking through simple doors and bring no weapons with them to combat their human enemy. Too, they are easily vanquished, humans learn quite accidentally, by water. Though the film was premiered to general critical acclaim, some critics blasted the script for these very reasons.
But the demon theory of the film solves this problem. The water left around the house by little Bo can be interpreted as holy water, famed among Roman Catholic exorcists for warding off demons and evil. And Bo herself? In a seemingly out-of-place exchange during the final confrontation with the creatures, Graham tells his daughter that when she was born, “all the ladies in the room gasped–I mean, they literally gasped–and they go, ‘Oh, she’s like an angel.’” In old Norse, Bo (Búi or Bua) means “to live”; the angel has brought the main weapon of life to be used against the forces of Satan. In a classic line from an earlier scene in the film, Bo wakes up her father to tell him, “There’s a monster outside my room. Can I have a glass of water?” This line deservedly elicits a great laugh from the audience; kids will be kids, right? But there is indeed a monster outside her window, as her father soon sees. Under the demon/angel interpretation, here Bo the messenger from Heaven is asking for the very weapon that she alone somehow senses will combat the demon/monster.
As in the case of the demonically possessed in the real world, Signs‘ “alien” is seemingly burnt by contact with the (holy) water. Note also that the “aliens” have cloven hooves, a classic depiction of demons in Western art since early medieval times. As stated above, the “aliens” also have no technological weapons; they rely on primarily on terror….as does Satan and his minions, who want nothing more than to have humans despair of their salvation and their survival.
Read the whole thing and think about watching the flick again.
I think it'll make it all the better.
And if you've not seen the movie yet, see it now.
Well worth the time.