Covenant's original title was Paradise Lost, the next is Awakening (for now).
https://en.wikipedia.org/wiki/War_in_Heaven
So this is it then. The opening scene in Covenant is heaven with Weyland as God and David as Lucifer. David falls from grace, and creates his army of demons. Almost certainly then Walter returns as Micheal in the future to defeat David. This explains the entire silly dual/battle scene between David/Walter in Covenant. The entire thing is basically Lucifer vs Michael round 1.
note : For those of you confused, the original working title for Covenant was Paradise Lost. Read the above linked wiki for more info.
So basically Ridley has turned the Alien universe into an allegory for the bible. Sneaky
lol this is an image from the story of Paradise Lost written by John Milton in the 17th century... look familiar?
https://en.wikipedia.org/wiki/Paradise_Lost