I think there are two Jacob-like powers on the island. One, which is now being represented by Christian Shepard, seems to have kept Michael alive long enough to ensure that the Oceanic Six leave the island, given Locke instructions that moved the island away just as the Six were returning, and sent Claire to Kate to tell her NOT to bring Aaron to the island.

The other, which is presumably Jacob, wants the Six to stay on the island, gave Jack medical issues to try and keep him there.

The scene from the first episode of the season, where there are TWO entities in Jacob's cabin, points to maybe this was the point where Jacob stopped being in as much control and "Christian Shepard" took over.

Yep I've been trumpeting the 2 Island forces for some time now... and you can add dream Claire not wanting Aaron to go back, yet Ben says they all have to go back including Locke's body to the list of indicators.

I think something like this is possible. Ther was discussion of disheveled Christian Shepard vs. clean cut Christian. they seem to have different agendas- maybe?

Although, "Christian Shepard" did appear to Jack during "Something Nice Back Home" in a capacity that made him freak out, pushing him to the "go back to the island" state of mind. I'm not sure how to parse this one exactly. Perhaps if he wasn't interrupted by the nurse, he would have said "Oh hey Jack, by the way, don't go back to the island. I'm your father, do what you're told."

Remember-two players, two sides, one light, one dark-two monsters, smokie and white light(from walkabout).

Science vs Faith too...

Ben = Faith, Widmore = Science?

1000000% in agreement with this thread.
The opposing forces are probably what makes it so hard to figure out the mysteries of the island- the clues are contradictory because they're coming from two sides.

Black and White stones FTW