Seeing Jacob (dressed in white) and the other dude (dressed in black) on the beach at the very beginning of the episode reminded me of God and Satan chit-chatting at the beginning of the book of Job. They seemed to be adversaries but still civil to one another. If that is who they represent in some way, God and Satan, Good and Evil, whatever you want to call it, it would make much sense.
Jacob keeps giving humanity choices, free will, and wants them to pick kindness, mercy and justice. The other dude, he just wants to kill Jacob, even appearing in the form of Locke to get Ben to do his dirty work.
What do you think?