The island is earth. The barracks is heaven. Jack is Jesus. Jack's dad is God. Jack will comeback to the island and serve as a "shephard" to those who are lost and bring them to the others. It's quite evident with the religious references (e.g. Eko's stick stating John 3:05. Read it and it makes perfect sense.
With all the references to all the different religions we can't find any references back to scientology?