"Signs" is,undobtedly, one of the most misunderstood films in recent memory. It is also one of the most brilliantly conceived and executed films in many a year. The heart of the movie lies NOT with the outward ET invasion, but with the father's inward crisis of faith.
The film asks the the timeless and difficult question that philosophers and theologians have asked for centuries. Is the world is just a hodgepodge of chance and coincidence, and therefore, meaningless, or is the universe guided by some metaphysical force, implying a purpose to everything that happens. Are we on our own, at the mercy of a cruel and unjust universe, or is there someone looking out for our welfare?
The director uses the alien theme to create a suspeneseful scenario ala Hitchcock, but infuses it with a profound, underlying structure ala Ingmar Bergman. He also throws in mystical elements such as the healing and life giving power of water ala director Tom Tykwer (of "The Princess and the Warrior" fame). The many layers produce a complex and thought-provoking film that should not be missed.