Nexus-Buffer Theory is premised on the speculation that Lost is a modern adaptation of Paradise Lost (with elements of Dante’s Inferno).
In Milton’s world view, the universe was represented just like the mobile above Aaron’s crib. The universe of planets, sun and stars was encapsulated by waters which fed the Earth and kept the raging forces of Chaos at bay. Outside the Universe sphere are the separate spheres of Heaven and Hell. In Dante’s work, after the rebellion in heaven, Satan and his devils were cast into Hell in the midst of Chaos. God then created a new universe which housed a new creature, Man, on Earth. Satan built a bridge to Earth through Chaos and brought evil to mankind, which lead to the banishment of man from Eden to the mortality of Earth.
In religion context, man has both a body and soul. Upon death on earth, one’s soul travels to another plane of existence. Some religions base that upon the sins of the past; others various stages of enlightenment and reincarnation; hell (punishment), purgatory (penance), limbo (pagan paradise) or heaven (resurrection, eternal paradise). In the afterlife, souls have new bodies (vessels). Various stages of the afterlife may be present in the ether of the after world, as the soul is cleansed of its mortal sins toward a path of enlightenment on final judgment. The mind would control afterlife matter.
What was left in Milton and Dante’s works was the revenge of Satan against God. There is an inference that Satan at some time would rise up to fight another battle for heaven. As Satan had found a path to invade his spiritual form to Earth, it would probably be much harder to breach the gates of heaven.
Thus, we get to the Island. The Island is a way station, a nexus point between the gates of heaven and the afterlife universe. The Hatch and the Numbers were the mechanism to maintain an electromagnetic barrier between the nexus bridge and the gates of heaven so Satan’s minions could not invade. When the numbers were not imputed to vent the EM, an alarm would sound, an internal barrier would drop and symbols would appear. I translated those Egyptian symbols to say “He escapes place of death.” Once the EM force field was down, breached or compromised, the nexus point (island) was exposed - - and other souls (devils) could arrive through either Chaos or through a gate to Earth to take control of this strategic place.
The basic assumption watching the show is that the characters are alive. They survived the plane crash. But in the jumbled time looping, flash back and flash forward story lines, is that really confirmed as true? It is possible to speculate that the passengers on 815 were already in their afterlives, having already died prior to Flight 815. In the flashbacks, there are clues that these characters died: examples -- Hurley: deck collapse; Kate: car accidents; Sayid: Iraq war casualty; Rose: terminal cancer; Rousseau: shipwreck; Desmond: lost at sea in small boat. They may not actually know they are "dead" per se, as their mind and soul is just beginning its long journey through the afterlife and judgment. (In ancient Egyptian culture, various parts of the body and soul transmute into the afterlife to be reconstructed after various stages of being in the afterlife.) How everyone got on the plane is like the comment from Defending Your Life, how one imagines their demise is how they are transported to the next level of existence.
Three characters have been called "special." If one looks at their situation with a more objective notion of time and place, one could conclude that they were either stillborn, or died shortly after birth. This would mean that they had no mortal sins. Ben (premature and born on roadside), Locke (mother hit by car, premature), and Alex (mother shipwrecked or died of the sickness). When Ben stated that he was born on the island, it may be a reference that he was actually arrived in the afterlife as a "rarity," a human soul without mortal sin. This would imply that he would have angelic powers. But those powers could be corrupted by other, fallen angels or Satan’s minions.
In ancient Egyptian culture (since LOST has increased its references to it as the seasons have come to pass), departed souls would reach a pagan paradise where they would toil in the fields of the gods, while others would go into the underworld to have their heart weighed in the final judgment on whether they would pass onto eternal paradise.
The Island could the the intersection of different, supernatural realms of good and evil. This could explain why our natural laws and physics seem not to apply to aspects of Island.