I've been rewatching the last episode about Richard, and I think that I just realized something. The island may actually be some kind of representation of the Greek version of hell. Remember how they said that you had to cross the river Styx to get there? There was like a boatman who would ferry people across. That is kind of like the ocean surrounding the island. There isn't someone who ferries them across, however there is some kind of invisible barrier around the island, and you have to travel at just the right trajectory in order to make it there. Not to mention the fact that Jacob is often the one who "brings" people there.
Anyway as I was watching the show, I realized that Jacob never actually denies the allegation that he is the devil. Instead he misdirects Richard by focusing on the fact Richard isn't dead. In Greek Mythology the living were allowed to visit Hades, and if they were dipped in the river Styx it would make them immortal. You may recall Jacob throwing Richard into the ocean.
After I thought about that, I remembered that in season 2 when Locke sees the invisible Hatch map that was painted on the blast door, it mentioned something about Cerberus being on the island, near the temple. I know that a lot of people speculated back then that Cerberus was the name that the Dharma Initiative gave to the Smoke Monster. If you remember, Cerberus was the dog like creature that protected the Greek version of hell, or Hades. It was also subject to do the devil's bidding. As you may also remember, the smoke monster has often been referred to as the protector of the island. And recently, MIB as Flocke told Ben that he needed him to stay on the island for him, and assume the role of "protector." All very interesting. Yet we know that Flocke wants to leave very badly, but Jacob explains the consequences of this to Richard in the episode. Can you imagine what would happen if Cerberus were able to get rid of its master, the devil, and was then able to leave Hades and enter the real world?
Also, Jacob tells Richard that he brings people to the island to see if they are corrupted, or if they will do the right thing. If I remember correctly, one of the jobs that Hades (the Greek devil) had in the underworld, was to judge those who had been accused of wrong doing in the overworld, to see if they should stay in Hades. Almost all of the LOST characters had done terrible things before going to the island that they were ashamed of, and so it stands to reason that maybe that is why Jacob, as the devil, continually brings those kinds of people to the island. He brings the accused there, and then gives each of them a chance to prove themselves either guilty of the crimes, or not guilty and that they have changed.
Is this making any sense at all? It does in my mind. This was a theory that floated around a long time ago, and the producers of LOST have said that some of the fan theories for the show are almost completely correct. What do you think?