What is the sacred story in Avatar?

Well, it's appropriate to discuss the actual meaning of
the word "avatar" first because also has connections to the sacred.  Avatar in the
religion of Hinduism is the term for a deity that purposefully comes down to earth.  The
deities of Vishnu and Shiva come to mind automatically.  In my opinion, this connects to
the movie Avatar directly in that humans are, in a sense, making themselves unholy
"gods" by choosing an "avatar" and invading the lives of the Na'vi.  On a more positive
note, the notion of an avatar connects to the movie because, through the help (the
will?) of Eywa, the main character of Jake actually becomes his
avatar.

This being said, the real sacred story in Avatar
has to do with the Na'vi and their religion which focuses on the worship of the nature
goddess named Eywa.  It is a sign from this Eywa that originally convinces Neytiri to
bring Jake back to her clan.  We learn throughout the course of the story that the
natural world, the Navi, and Eywa are inherently connected (hence the danger of them
leaving Hometree to its destruction).  A cornerstone of this link is the Tree of Souls
where the Na'vi can communicate with various forms of indigenous life on Pandora.  This
connection is again apparent when the animal life of Pandora "defeat" the humans with
the aid of the wounded Na'vi.