The title of Alien: Covenant directly refers to the spaceship carrying the film’s human characters, and indirectly refers to the film’s most pervasive theme: The tense relationship between gods and their creations. Students of the Old Testament learn about God’s covenant with Abraham, which promised the prophet the land of Israel in exchange for, among other things, his male descendants’ foreskin. Some gods work in mysterious ways; the ones in Alien: Covenant certainly do.
The assassins of Assassin’s Creed have an assassin's creed that they recite repeatedly in Assassin’s Creed. (If that mere fact alone makes you smile, you’re in for a treat.) This creed involves the phrases like “nothing is true” and “everything is permitted” (the assassins are the good guys in this movie, by the way) and concludes with the declaration "We operate in the darkness to preserve the light."