there is no good or bad by drsp58

Many believe that Jacob is the good guy and MIB / New Locke is the bad guy. There are reasons for this: the good guy is represented by white (clothing, white stone in 6E04) and the bad guy by black (clothing, black stone, smoke monster). Furthermore, the bad guy kills (smoke monster). These symbols are so generally acceptable that they remain undiscussed. Consequently, the bad guy should be avoided by the characters whenever possible.

In my theory, the latter will show be false and hence the bad guy is no bad guy. When sat on the beach, by body language or by spoken words, neither Jacob nor MIB was clearly good or bad. They represented more likely opposite views: Jacob drawing people towards the island and MIB keeping people off the island. I even dare to say getting people off the island, since as New Locke declared to Ben after Jacob was killed: contrary to Jacob I want to go home.

Now suppose that for the sake of the main characters it was somehow necessary that they first are brought to the island (by Jacob) to be returned to the present time later (by MIB /New Locke). A detour so to say from the expected route (the current Alt timeline). To what purpose I don't know: At first I thought that their fate in the Alt timeline would be so unfortunate, that a return from the island would show to provide a better outcome. However, thus far the Alt timeline works out just fine for the main characters. So I'm a bit short on purpose now, but the general idea stuck: they needed Jacob to go to the island and now they need MIB/New Locke to return safely. MIB had to take Locke's identity for this since that would be his only chance to be accepted by the characters (Locke had credit with many of them).

One of the main reasons I like this theory is that, if true, it will lead to a drastic change in general opinion about the role of MIB/New Locke, thus providing an unexpected surprise. It will require a change of mind by the characters not to feel sheltered in the temple but to reunite with New Locke, who they now see as the enemy but who in fact they need to survive.