I don't usually try to think too far ahead of LOST and figure out all the different mysteries of the show. I'm content to just follow along at its own pace and enjoy the answers as they come. But as I was driving yesterday, I came up with half a theory I thought I'd put out there.
In the same way that John Locke has seemingly had to die to bring the Oceanic Six together and back to the island, what if Christian Shephard died to bring the original Lost crew to the island? I have no idea about the why of it but I like the cyclical nature of my theory.
Feel free to discuss amongst yourselves.