prometheus spoilers (2) -
jason has been talking about the movie all day and he linked to this article which has the following line of shear brilliance:
Two thousand years ago, humanity not only murdered the Engineers’ emissary, it infected the Engineers’ life-creating fluid with its own tainted selfish nature, creating monsters. And now, after so long, here humanity is, presumptuously accepting a long-overdue invitation, and even reawakening (and corrupting all over again) the life fluid. .
the emissary he refers to is jesus and his assertion is that the black (primordial?) fluid that in the opening credits seeds life on earth is affected by the emotional or mental state of those who come in contact with it. so, by killing their jesus humanity created the xenomorph alien creatures via our foul view of ourselves as the center of the universe.