The seven deadly sins can be represented by the characters. I found some differences in what the 7 deadly sins are but here goes nothing. Let me know what you think.
Lust: Sun (has an affair on her husband even after Jacob touches her and lets her and her husband not to take their marriage for granted.) Gluttony: Hurley (obvious reasons) Greed: Kate - steals, robs etc, takes what she wants (men, lives,or items) Sloth: Charlie - gets addicted to drugs, has never really worked for anything other than his one hit song Wrath: Sayid - he is ready to kill and has done so many times Envy: Locke - he wants to be like his dad, he wants to be the leader, he wants to be able to go on a walkabout Pride: Jack - he wants to fix everything, everything has to be perfect, he didn't like being embarrassed by his dad during surgery (he even turns his dad in later)
All were touched by Jacob except for Sayid and probably Charlie, although we are not sure. I think this helps them to overcome their natural tendencies and to choose good (free will). I believe that the fade to white will cause all of the characters to jump to the future (present) and get ready for the final battle.