An interview of Ridley Scott gives some clues: Movies.com: We had heard it was scripted that the Engineers were targeting our planet for destruction because we had crucified one of their representatives, and that Jesus Christ might have been an alien.
Why did the Engineers want to go to Earth?
Scott himself likened this superior race to the dark angels in Milton's Paradise Lost and the symbolic etchings of William Blake. Hence, the reason why the Engineers were heading to Earth was to annihilate the human race, possibly with the aid of the bioweapons they had created.
Why did the Engineers create the aliens?
In Prometheus, the crew that lands on LV-223 and assumes that the abandoned moon was some kind of tactical development outpost for the Engineers, meaning the proto-humans created the xenomorphs as a highly specialized biological weapon to eradicate a planet's population as they conquered worlds.
Why were the Engineers hostile in Prometheus?
He realizes that humans are still violent and corrupt spiecies who are also capable of interstellar travel which makes them even more dangerous to other Engineer creations. It is no surprise that the Engineer kills the human crew and proceeds to destroy Earth.
What happen to the world without engineers?
Restaurants would be left without stoves and ovens, and prepackaged foods would be without packages. 2:00 p.m. The Work Environment What work environment? Without engineers, there would be no heat, air conditioning, photocopier machines, conference calls, printers, e-mail, or World Wide Web.