[StainlessSteelCynic]

Alien 3 gets a lot of flak (not unjustifiably) because it is a flawed movie. Unfortunately there was constant 'creative' interference from the studio during filming and the movie that director David Fincher actually filmed was, in the end, butchered during the editing and final production to make the movie you all know and loathe.

The original concept for Fincher's movie was that the prisoners on the planet had basically formed a monastic society to cope with their life imprisonment. They had become religious and devout in their obedience to their faith and the feel of the movie was supposed to convey a sense of monasticism, the mythic qualities of gothic cathedrals and the organization of an ordered lifestyle that is upset by the arrival the 'outsider' and the chaos she brings.

Ripley's arrival brought with her the fear of the serpent being released into the "monks" Garden of Eden (note that in the pre-Christian beliefs of Europe, the serpent and dragon were one and the same, although not specifically associated with evil, so the references in the movie to the dragon can be explained - unfortunately this is lost in the theatrical release). Ripley brings with her the Alien, i.e. the dragon, the evil that will bring chaos and destroy the life the prisoners have been leading.
If you can see the 'Assembly Cut', a lot of the removed footage is restored and more of what Fincher wanted to achieve can be seen, it does bring a different feel to the movie.