I would have to agreed to I definitely think the series is based on biblical references. I am not sure whether it is purgatory or not though. My theory is

and take it with a pinch of salt and I have not worked out all the answers and most likely it is wrong.
I think the island is a special place where there is a 'ladder' that leads to heavon. Hence Jacob and Jacob's Ladder from the bible. This was a special place in the bible where angels could come down to Earth. Hence why we keep seeing 'ghosts' I suppose. Jacob had a falling out with one of his brothers and the two lived separately for many years with a river separating their two lands. The island is separated into two lands.
In the bible Jacob had as on called Ben whose Mum died giving birth to him, this is true of Ben in our Lost. Ben was in charge of protecting Jacob's lands from the Juda land (or something like that). This is what our Ben appears to be doing protecting the island.
Dharma means something like improve your life. Each week there does seem to be some reference to religion in some form or another. Miracles appear to happen with John walking, surviving the bullet, Miquel coming back to life, etc too.
I am too tired now to think of any other coincidences but it is fun trying to work it out and to throw my ideas into the pot.