The Collapse was like the apostasy, and the ghosts were like the restoration of the priesthood, apostles, church, etc. (multiple religions have different views on apostasy, mostly Mormonism). I'm not preaching or anything, but I find it cool how Bungie would incorporate ancient texts into a game. Not for religious purposes, but for knowledge and symbolism. P.S. one of the Bungie head developers is a Christian, (Mormon.)