[syke123]

My final speculative thoughts.

Spoiler for Maybe:

Mana has been confirmed as "Eve", "Baima", lucifer.
Shu should be considered as "Christ", "Macroprosopos".
Inori should be considered as "Virgin mary", "Microprosopos", since she is a pure reincarnation.

So following the Kabbala denudata "Unveiled", the following may happen.

Shu kills Mana and the world dies from the virus, he then repopulates the world with Inori.

Shu doesn't kill Mana and she continues to reside within Inori, two children are then born one for the next son of god through Inori, and the other gives birth to humanity through Mana.

Shu is a sacrifice to bring forth the new age with Inori, rejecting Mana, Inori gets pregnant with Shu's child, and is reincarnated as the child.

Shu saves the world, rejects Mana and she disapears alongside Gai, the apocalypse is then prevented.

Probably one of the above.