Alright, I figure I better put this down in some form of "official" status so you all can get where I'm coming from. This is a very abbreviated version but my theory goes as such.
The island is effectively the land of the gods. It is a place that is possibly the source of their power and that is something that Science, wants to harness. Science may have come in the form of the Dharma Initiative and the Hanso Foundation which seemed to do things on the island in an experimental fashion to control in a scientific way the things that gods in their omnipotence take for granted as in teleportation, time travel, immortality etc etc. I have felt that our main group of people were people who hadn't known they were gods but were being summoned back to the island to possibly defend it from another onslaught of Science, or potentially new gods.
Much of this came from similarities to Neil Gaiman's novel American Gods. I suggest picking that up if you haven't read it. It deals with the concept of gods as tangible beings who's strength and existence depends on the level people believe in them, like Tinkerbell or Candyman. They also don't always realize who they are, weird things happen, certain people of power guide them in mysterious ways, and they often don't die. So much like Lost that I am shocked that it hasn't wound up on their "someone on the show is reading it because it means something, or we just plain like it list" which I attribute to it being too much of a clue. Or I'm just arrogant and looking too much into it.
So I came up with this theory a couple of seasons ago and as things roll on it makes more and more sense. For starters, these people clearly don't die or age. Claire was a big one as well. You think that after vanishing, losing her child, then winding up in a shack with her dead dad who she never really met would have her pretty freaked out, but it seems that she was pretty comfortable and at home almost as if some sense of purpose had been re instilled in her.
Then this season I was watching and had my Richard Alpert/R.A./ Ra flash. I realized that the eyeliner man that I had figured may have been an Egyptian god was clearly like, the Egyptian god Ra. Could Horace Goodspeed be Horus? What about the Black Woman who drugged Michael and also was a nun in Eko's childhood?
I am also wondering if Eloise is "God" and Widmore is "Satan" and they are battling for control over the old gods who now inhabit the island. But not totally sold on that one yet.
I realize at this point I'm beginning to sound like some nut with a manifesto, but I just wanted to throw it out there for you all.