adapted from a comment I made in another thread:
Please don't hate me, but this is another post about MIB's claim to be Christian. I know, I know, everyone is sick of it. People have gone in circles talking about whether the freighter and hospital appearances could possibly have been MIB. This post isn't about those that. Instead, this post is about what I see as a glaring inconsistency that has gotten little attention: the case of the missing body.
During Season 5, the show made a huge deal out of the fact that Locke's body was still in his coffin. This was apparently proof that it wasn't really Locke who was wandering around. It was so important to Ilana, an apparent Island expert, that she dedicated her entire squad to carrying it first to Jacob's cabin, and then to the foot. This body was serious business!
Much earlier on, the show made a huge deal out of the fact that Christian's body was missing from his coffin. Then in Season 6 we get a refreshed reminder of the missing body: not only was Christian's body missing on the Island, it's also missing in the FST! How weird is that? This seemed to imply that Christian might be up and wandering around. This lack of body is serious business!
So, there's a generally accepted theory that MIB was manifesting as Christian all around. Am I really supposed to believe that "body not missing + dude walking around" is the exact same thing as "body missing + dude walking around"? If Ilana was around for Christian's early appearances would she have told everyone to be cool since there was no body? There has to be more going on here.