Christianity is a religion rooted in historical claims and historical narratives, as is the Judaism from which it emerged and whose scriptures it shares. On the one hand, their linear narratives of salvation history locate cosmic and essential significance in particular highly specific events, people, places, and times. Yet on the other hand, Christianity has been from its earliest centuries a highly philosophical system. Great weight has been attached to metaphysical propositions about the relationship of the divine and the human that are claimed to be absolute and timeless. The history of religion, therefore, embraces both the history of peoples and the history of beliefs and teachings – teachings that, to some extent, claim to defy the flow of historical change. The business of doing religious history intrinsically threatens some aspects of traditional belief. It challenges the claim of certain doctrines to be timeless, or to be rooted in the universal consent of the faithful. It illuminates the context-driven character of so many of the church's decisions and pronouncements. Finally, it analyzes the often highly mixed and often discreditable motives and behaviors of key players in the messy business of religious politics.

Like its subject matter, religious history has evolved considerably across two millennia. In part, the evolution simply reflects the changing intellectual cultures of different epochs, the constant and inevitable dialogue between a world faith and the particular cultural matrices in which it grows and finds expression.