'Lost' Answer - Why They Were Chosen

In episode 1x24, Exodus Part 2, Locke told Jack, "We were brought here for a purpose, for a reason, all of us. Each one of us was brought here for a reason." What was that reason?

• We know that they were brought there as potential candidates and that Jacob picked them because each of them "needed the island as much as the island needed them (Ep: 6x16, What They Died For)."
• Since the journey to become the island's protector required so much mentally and physically, so much soul searching, so much danger, some were picked to help those chosen to achieve their final goal. Did Jacob choose Sawyer because he thought he would be a good candidate or did he just think he would be a no-nonsense tough guy that could be a lot of help for the actual candidates? Same way of thinking, did he pick Hurley for comic relief or for the insight he grows to possess, which enabled him to be a protector.
• The survivors where initially brought to the island to confront each of their flaws from the real world. Jacob?€™s candidates were given the chance to reveal to Jacob the qualities required to become the protector of the island. The issues became more complicated as MIB/Smoke Monster/Christian/Man in Locke joined the game (i.e. MIB in the form of Christian led Locke into false leads, MIB in the form of flash forward/backs Locke led Richard and Ben into false leads). From that point on, Jacob and MIB were on a course toward each others' destruction, and the survival or destruction of the island.
• Any person who has a flaw or weakness, according to Jacob?€™s law, will visit the island in his or her life. In this way they might be improved if their mind is good or diminished to a monster if they are bad. What we watched was only a group of people (Jack, Hurley, Kate etc). The water/light which is protected by Jacob is actually our mind, if you?€™re going to protect it from bad things you have to fight with evils or you may leave it for anything to come in, so evils will get in and destroy it.

Get in on the discussion of chosen island folk.