The beginning and the end of the apocalyptic world of sins

The world after the bloody war between God and Darkness. God won the first war but the Darkness using the weak minded humans and the seven sins to take over humanity. Transforming the humans into demons just like the first war. This time around God has mysteriously disappeared and his holy virtues are killed and the only beings left to defend Gods creations and the univserse he has created are the elder seraphim’s. The story revolves around a boy named Gabriel who must take his rightful place as one of the 6 holy virtues of God and defeat the darkness that corrupts his universe once and for all.