The ones who don't age - Richard,, Jacob, Locke/SMonster, and I'm guessing Togan (Asian guy) were the original archangels. Richard - St. Michael - is the defender in battle. He has always been in the midst of the battles. Jacob - St. Gabriel - the messenger. He delivered messages to the "candidates" and was said to have led them to the island as candidates. Togan - St. Raphael - healer. Jacob said he needed Hugo to bring Sayid to the Temple to be healed. And if there were 4 Archangels - the fallen - SMonster Lucifer wants out. I suspect his job could have been protector of the island, which he thinks doesn't need protecting, and always felt less in God's eyes or slighted.
God is looking for a candidate to take the place of Locke/SMonster who wants to leave. Jacob has been bringing people to the island in that search. God could have made his appearance as the child telling Locke/SMonster that he was supposed to play by the rules and not kill him (Jacob).
I also think the ones who are in the temple are being shown what their lives would be like if they went back and because of free will - they will be given a choice.
Also, Jacob and Locke/SMonster's differences are becoming parallel to Jack and Sawyer. Sawyer has "teamed up" with Locke/SMonster and Jack seems to be headed to an alliance with Togan.
Any thoughts????