As a very early adopter of "they're all dead" theories of the show premise, the cork analogy fits nicely into my Nexus-Buffer theory that the island was a gate-portal between heaven and hell to stop Satan from attacking heaven. There are contradictory stories in religious texts that once Satan was banished from hell and thrown into the lake of ice in the depths of the chaos universe, he still had the power to visit Eden and Earth to spread evil, temptation and undermine God's word. An example is Richard's wife, Isabella. She died of the plague, the Black Death. There is an inference that even if Satan is locked up in hell, his evil can still make its way into human existence.
LOST has appeared to mold a "consensus" idea of the devil-evil theology into a secular form, an island prison, with a person called the "devil" trying to escape, and a "guardian" or guard trying to keep the wine (evil) in the bottle. And in a consensus like structure, not fully confirmed at this point, the idea of "dead" people showing up in a place of the dead (hell, purgatory, limbo, the island) is not a far off idea. It makes perfect sense. Having these people appear only to some people as ghosts and to others as living humans, it could be explained as hellish mind games or punishment. As for "killing" dead people on the island, this could be weaved into several concepts that when a person dies his or her soul is reincarnated in the afterlife to make a journey of redemption, and along the way it could be destroyed or saved to pass on to another existence (a bad possibility would be the sideways world, where too many conflicting variables make it into one happy, sloppy finish to the epic story).
I am also wondering if the "infection" on the island is the Black Death in the underworld. In the real world, one contracts the disease and dies, releasing your soul to the after life. In the afterlife, one's soul contracts the disease and turns into pure evil.
