Christianity is a remarkably diverse, global faith. It makes no sense to speak of Christianity in the abstract, any more than one can make blanket statements about Islam, Hinduism, or animistic religions. For an introduction to the subject, see the following:

Philip Jenkins. The Next Christendom: The Coming of Global Christianity (Oxford University Press: 2007)

Philip Jenkins. New Faces of Christianity (Oxford University Press: 2008)

Lammin Sanneh. Disciples of All Nations (Oxford University Press: 2007)

To get an idea of the diversity of beliefs and practices even among the very limited subset of (mainly) Protestant denominations in the Southern highlands, see the following:

Fred Brown, Jeanne McDonald. Serpent Handlers (John F. Blair Publishers: 2007)

Richard Callahan Jr. Work and Faith in the Kentucky Coal Fields (Indiana University Press: 2008)

Bill Leonard. Christianity in Appalachia: Profiles in Regional Diversity (University of Tennessee Press: 1999)

Howard Dorgan. In the Hands of a Happy God: The 'No Hellers' of Central Appalachia. (University of Tennessee Press: 1997)