Abstract: Christianity has experienced a conversion of “edge--center--edge” because of its cultural value orientation. There were two main characteristics in the spiritual world of the Roman Empire: materializing and hollowing. This actually was the historical condition in which Christianity spread and achieved dominance finally. Christian victory shows that a mainstream culture which can provide moral sublime is essential for maintaining a political framework. Medieval Christianity, which once flourished with the moral sublime, copied the corruption of the Roman Empire and eventually declined because of morality loss. In fact, regardless of its actual state, the existence of a society always depends on moral support, and this is a basic law of building the mainstream culture.

Key words: Christianity, the Roman Empire, morality, the mainstream culture