When the finale first ended last night, I was disappointed. Processing it late last night I realized I was disappointed mainly because it challenged my belief system. It is easier, somehow, for me to believe in plane-crashing electromagnetism, multiple timelines and nuclear blasts that propel characters through time than it is for me to accept the vision of death and pathway to Heaven that we were presented with. I mention this because for six years I have watched the show and accepted that the Island is special, that it could heal the sick, prevent aging, etc. etc. I didn't need for it to be heaven, or heaven's gate for me to accept it as reality, albeit a highly fantastical one. If you can accept that in the Lost universe the "real world" holds a magical Island, I believe that addresses issues like semi-immortal humans and the light that must never go out. It's a special place, and it doesn't need to be heaven to be filled with magic and wonder, at least in my interpretation. Some of the questions you pose seem to have been addressed already. Or at least seem easily explained to me. Polar Bears: I always assumed the Polar Bears were brought to the Island by the Dharma initiative, and the one in the jungle escaped from the cages, or was let loose, sometime after the purge. They may have even been using the bears as part of their experiments in time travel. Didn't Charlotte fine polar bear skeletons in the desert? The Walking Dead: Manifestations of the MIB, trying to manipulate people to his agenda. Eko's brother, Dave from the asylum, Christian. They were all part of his long con. Infertility: A result of the incident/nuclear explosion. Murder/Hell: This seems to me exactly why Ben is still in the Purgatory of the flash sideways. He still hasn't come to terms with or made amends for his life, and isn't ready to move on. Whether he can't let go, or he's afraid of being judged, I am not certain. I do like this representation of an afterlife though, because it seems to understand that no one is purely good or evil. We all have shades of grey. It's comforting in the Lost universe that people can do bad things and not be punished for them eternally. The nuclear radiation: If the Island could cure Rose's cancer and heal John then I guess it could bring vegetation back to life in a fall-out zone. Though in fairness this might contradict the infertility theory. No matter how you slice it though, life or afterlife, I think we either accept or reject the universe in which this story happened.