In white Rabbit Christian is in a suit wearing white tennis shoes, we also see him in the suit at the cabin when Hurley goes there. When Claire see Christian he’s wearing a stripped shirt. When Locke meets Christian in the cabin and at the frozen donkey wheel he is wearing a different shirt.
How does a dead man have a change of clothes? I believe both Jacob and MIB have been using Christian. When Christian is in the suit he’s Jacob and that’s the image Jack had of his father. When he’s with Claire and Locke I believe he is MIB.
I believe MIB has been manipulating events so that Locke would turn the frozen donkey wheel and get off the island and die, then MIB could become Locke. MIB posed as Horace and came to John and told him how to find the map to the cabin.
One problem instead of Locke turning the wheel it was Ben who did and the wheel became dislodged creating time skips. Flocke tells Richard to tell Locke that he has to get everyone to come back and he would also have to die. Flocke has to make sure this happens or he can’t be Locke for very long.
Locke goes down to the donkey wheel and talks to Christian who conveniently backs up Richard’s story about dying. Why? Because that’s really MIB posing as Christian.
So Locke is killed by Ben ensuring that a loophole has been created for MIB. Hawking tells Ben they have to recreate flight 815 as best as possible.
Jack is Jack. dead Locke is a proxy for Christian. Handcuffed Sayid is a proxy for Kate. Kate is the proxy for pregnant Claire. Ben is proxy for the late arriving Hurley.
Lapidus who was suppose to pilot 815 is the pilot for 316. What MIB didn’t plan on was that Jacob had his own team on 316, Ilana, Bram and company. Ilana said what they had in the box was a weapon and it turned out to be the body of John Locke. I’m not sure how Ilana will use dead Locke against Flocke but it should be interesting.