Ok, I am late posting....but I am going to add a few cents to this conversation.
1) The religious complaints have already been answered, but I will say personally for me it wasn't over done, nor was it too much one religion or another, and just because a statue of Jesus was shown doesn't mean they were pushing Christianity...in fact as a Christian I find the story rather confusing as any form of Christian allegory.
2) About answers to the island. I think one of the best parts of Lost is only knowing what the characters know....and only understanding what they understand. Remember Danielle once said the smoke monster was a security system. We took that as absolute fact, but in reality she had no idea what it was. Where does this place learning about the island and the light? It is obvious not even Jacob or the MIB understood what the light or island was. Jacob was told very little from his mom about the light and island. And he protected it the best he could. His mother probably wasn't the first protector and probably didn't know everything.
So this means we don't know everything. Now this may bother some people, but the writers of Lost have always said they were more focused on writing about the Characters and their drama instead of focusing on the island. It means that characters acted on one understanding that we also believed but something else entirely happened. (Charlie dying to send the helicopters to save Claire.)
I think we got most of the important questions answered, and some questions left unanswered were probably dropped story arcs or are elements you can probably fill in the blanks with what we know now. The hardest one to deal with is why was Walt special and what could he do. But the Walt storyline was dropped because the actor was growing too fast.