We know that Jacob's enemy has been impersonating the dead body of John Locke. It has appeared over the years that somebody has been incorporating the body of Christian Shephard. In "Cabin Fever," Christian Shephard, assumedly on behalf of Jacob, told Locke to move the Island to protect the Island from Widmore's freighter. I'm under the assumption that during our time viewing Lost, Jacob never lived in "his" cabin, he lived in the shadow of the statue and imprisoned Jacob's enemy in the cabin. Somewhere along the line, the ash circling the cabin was broken (maybe by Claire?) freeing Jacob's enemy, and allowing Jacob's nemesis to freely move about the Island, and impersonate Christian Shephard. I believe that the Christian Shephard on the Island that Jack saw was merely an apparition, but by Season 4 Jacob's nemesis/the Monster had full control of Christian. SO Jacob's nemesis told Locke to move the Island because he doesn't like new people coming to the Island, a fact that he told Jacob in the opening scene of the finale. He was able to make it seem like it was Jacob because Jacob is the protector of the Island as well. Moving the Island was beneficial to Jacob's nemesis because 1) new people wouldn't come to the Island and 2) it would send Locke on the time skips, assuring that the time loop where Locke becomes leader of the Island is realized, and where he'd leave the Island to die, therefore Jacob's nemesis could take control of his body to tell Richard to tell time-traveling Locke that he had to die, and use Ben to kill Jacob.