Halo 2 delved a bit more into the story line of the aliens attacking the humans. It seems the alien culture is based on a religious cult they call “The Covenant”. Halo 2 reveals that the prophecies the Covenant is founded on are false. The leaders of the covenant are trying to cover up this fact. The result of this false prophecy is leading the aliens to activate the dormant Halo space stations which are really weapons that will kill all life in the galaxy.
I liked the game, but I’m suspicious that the game is turning into a message that religion is just a tool to lead gullible people. The only religion discussed in the game is a religion that is false.