At the end of the final episode, 6x17, The End, the Losties gathered at the church before moving on to whatever was next. Ben was there and obviously invited, but he did not go in. Does this mean he was evil and could not go into the light with the others, or somehow or other, he is still alive and could not enter?
My answer is that he was just not ready to move on. He had found his place with Danielle and Alex and needed to work through those feelings and make up for past issues. Also, he may have wanted to wait until they were ready to move on so that he could move on with them.
What do you think?