I've never taken up this many post for one show, but there is so much going on in this episode and I have a lot of thoughts but I wanted to do a summary of the episode just for reference, so this is the Dharma plotline here and here is the Jacob/Locke plotline. This is for my thoughts and theories.
So the part that interested me the most was Jacob and the other guy who I call OG. OG wants to kill Jacob but he can't so he has to find a loophole and he finds it in John Locke and Ben Linus. But what I'm wondering is if he was locked in "Jacob's" cabin and couldn't get out because of the line of ash. And that is who Ben thought Jacob was and who Christian Shephard is working for and who whispered "Help me" to Locke and told him to move the Island. Maybe he told Locke to break up the circle of ash because when Ilana and her group arrive, there is a break. Also Ilana says that "he" (Jacob) hasn't been there is a long time and that someone else was using it. I wonder too what connection Not!Locke/Christian has to the Dead!Alex since she told Ben not to try and kill John Locke again. Is the Smoke Monster, called Cerebus, an ancient god of death?
So OG gets out of the cabin and manipulates the situation so that Locke thinks he has to die to bring everyone back so Locke goes and does that and OG can then pretend to be a risen Locke and get Richard to bring him to Jacob. But he can't kill Jacob himself so he gets Ben, who is suffering from an amazing disappointment and heartbreak, to do it. That is what makes me think that OG has been Christian all this time and he was using him to try for Jack first but when that didn't work he started on Ben.
My theory is that this is some sort of god fight. I think one of them, possibly Jacob, is Sobek, the crocodile god ("he was a repairer of evil that had been done, rather than a force for good in itself"), and that the other, OG maybe, is Set (the desert god, bringer of necessary chaos). So Set cannot kill Sobek directly for some reason so he sets up a situation that will bring about Sobek's death. When the Black Rock was sailing to the Island (1845), they have a conversation about Jacob bringing the ship in order to prove to OG that he is wrong. Jacob says maybe this time will be different. But OG says it always ends the same; they come, fight, destroy, corrupt. Jacob says it only ends once, everything that comes before that is progress. So it seems that Jacob wants to prove that people can be good and that OG thinks that they are not. It also seems that Jacob keeps bringing people to the Island in order to prove OG wrong because this is not the first time he has done this. I wonder if he had a hand in the plane crash. He certainly seemed to hand pick everyone over the years.
Another god possibility is Taweret, the hippopotamus goddess of childbirth. She was demon-wife to Apep, the god of evil, but also seen as the consort of Sobek. So the statue is either Sobek or Tawert. Maybe the fight is between Set and Sobek over Taweret. I don't think so but then it's always about a girl.
ETA: ABC confirmed the statue to be Tawert but I still hold to the god fight theory.
Or it could be that it is a very literal thing and Jacob is just Jacob and OG is Esau, his brother, straight from the Bible. According to the Bible, Jacob and Esau are fraternal twins with Esau being the oldest. He "sells" his birthright to Jacob for a bowl of lentils bean. Later, after Jacob tricks their father into giving him his blessing, Esau threatens to kill Jacob, but is stopped by their mother who favors Jacob. They reconcile later in life. I'm just throwing all this out there. I'm going to stick with my original idea though.
Back to Cerebus and the Temple, when Ben is shown his daughter's death by the Smoke Monster and then attacked by Dead!Alex and made to promise that he would help Locke out, I wonder if the Monster and OG are the same or working together. Is OG the master of the Monster or the Monster himself and that is why he made Ben promise not to try to kill Locke again? Since he was physically acting like Locke, he didn't want Ben to kill him before he had a chance to kill Jacob. I'm thinking of the hieroglyph that showed a god summoning the monster.
Also when Ilana asks Richard what lies in the shadow of the statue, he answers he who will save us all. Now I know this question and answer were probably provided by Jacob himself but I think that it is very telling since Jacob is the one who lies in the shadow of the statue.
As for Richard, I wonder where he came from. He tells Locke that he is this way (ageless) because Jacob made him that way. I think he was on the Black Rock and is the first mate whose journal was discovered. Although, I am probably wrong since he seems to be older than that, but Jacob seems to have made him so he can be adviser/protector of the Leader and the go-between the two, Jacob and the Leader, and take care of the Island when Jacob is gone. He seems just as confused by events as everyone else and doesn't seem to have any extraordinary powers beyond being immortal. Would he recognize OG if he saw him as he was in the beginning? Does he know what he is and what is going on between the two of them?
This is how I describe it to BT: "So a whole bunch of stuff happens and Locke ends up being possessed by this old guy we saw at the beginning of the episode who was looking for a loophole to kill this other guy and he talks Ben into doing it. And Ben is like stab stab stab and the guy falls over. But I think it's about gods fighting."