I believe that the smoke monster is in fact Jacob! Last episode Ben warns Danielle that if she ever hears whispering, to run the other way. Any time anyone is in search of Jacob and his cabin, you also hear these whispers. I believe Jacob/Smoke Monster can manifest dead characters, and in a sense, reanimate them. I believe Christian, Locke and Alex are all truly dead, and it's simply the smoke monster manifesting itself in their bodies. This could be why last episode when Ben summons the smoke monster, he doesn't appear, because Locke is already near. Ben mentions to Sun, whatever comes out of the jungle, be prepared to run...Then Locke appears. Also while in the basement of the temple/wall, John leaves, Smoke Monster appears, Smoke Monster leaves, John returns...I think this also explains why John has become a much more dark/bolder character, and why he now knows more about the secrets of the island...Just as Al! ex was evil when confronting Ben... Theory by G_O_N_E
