Okay so here is something I noticed after doing some unrelated research.
Many People have heard of the seven deadly sins but many may not be aware of a verse in Proverbs that lists the six things that God hates and seven he detests. Here is a list and how I think they might pertain to our candidates.
1. Haughty Eyes
2. A lying tongue
3. A hand that has shed innocent blood
4. A heart that devises wicked schemes
5. Feet that are quick to rush into evil
6. A false witness who pours out lies
7. A man who stirs up dissension among brothers
I believe we can assign many of these sins to most of the candidates but I think their flashbacks in Season 1 were a clue to which one did what.
1. Hurley - He had haughty eyes because he desired to win the lottery. It's may not be sin in many peoples eyes but it is a representation of greed. And what happened? It ruined his life.
2. Locke - There are two of these that have to do with lying. This one I believe has to do with a constant sort of lying. Someone that lies all the time. One lie to cover up another. While this may seem like Sawyer, Locke lies all the time about his life, mostly to himself. He tells everyone he is not handicapped and can do anything. He lies to himself because he is in denial about where and who he is. His denial is indeed ruining his life too.
3. Sawyer - This one is pretty easy. He shed the blood of an innocent man just before getting on the plane. It may not have ruined his life yet but things couldn't have looked worse for the con man.
4. Sun - This one may also be a good description of Sawyer at first but in Sun's flashback she was devising a scheme to leave her husband. The clue here is "A heart" that schemes. She let her heart lead her to adultery. Of course it was also ruining her life.
5. Kate - Obvious similarity here. Her thing is running. And the more she runs the more evil she finds. Needless to say it has ruined her life.
6. Jack - This is the other that has to do with lies. While lying may not seem like a trait exhibited by the Jack we know, the Jack in his flashbacks was indeed baring false witness against his wife and father, accusing them of having an affair. That's the form of lying to which this item pertains. He has bore false witness against another. And what happened? It ruined his life.
7. Sayid - This is the only one that we have to stretch things a bit. Sayid was a torturer in Iraq. He is working for a regime that indeed stirs up dissension among brothers. His job was to turn brother against brother in a literal way, not just a general way, in the sense that we are all brothers. To be honest I first had Sayid as Number 3 instead of Sawyer but Sawyer seemed to fit 3 better. Sawyer could fit here as well however as a con man could easily be someone who divides people in order to run his con, but it's not a really good representation of either candidate.
Now I know most people are going to scream that "Kate ISN'T a Candidate!!!" Okay but she was. Locke's no longer a candidate either.
I also realize that this theory seems like it could have been written immediately after season one and indeed it was seeded there although I was trying to relate it to the seven deadly sins. But it wasn't until now that I found a way to fit it into the grand scheme of things on the show. So here goes.
If we believe Jacob that everyone that comes to the island gets a blank slate and that their previous life doesn't matter then we have to assume that none of them had to pay in any way for their sins. Their slates were wiped clean. No sinners. No need for redemption. That is until...they start to sin on the island. NOW they're once again sinners. Running their games, telling their lies and shedding innocent blood. Unless they redeem themselves they may be stuck just like Michael.
Now to the crux of my theory. What if everyone who is brought to the island is brought there as an embodiment of a particular one of these things God hates or as one of the seven deadly sins. What if the MIB is trying to get the candidates all together so he can leave the island with all of the things God hates and detests. Maybe he has to have all of the things God hates in order to leave the island. Maybe he will feed on that sin during the long plane ride home and use the candidates as a snack.
Is this a stretch? I'm not really convinced myself but wanted some input. Let's have it.