The Group Dynamic Theory

It's all about the group dynamics. When certain people fulfill their roles they are being taken by the others, because they're not required for the group to develop anymore. The island seems to respond to each person personality - the better person you are, the more generous the island is. The smoke monster seems to represent death or fear - if you're not afraid the smoke monster doesn't influence you. He is obviously fake - the sounds he makes suggests that it is man-made. The others know some secrets of the islands that losties don't but they only include those who are worthy - they just take them and include in their group when they're ready. Those losties who are bad lose their life by the hand of the others because their presence "pollutes" the island somehow. The island seems to enhance the psychic powers of the inhabitants - that's why it is important to have only good people living there.
Theory by: con