The distinction that is now drawn between natural and revealed theology evolved gradually. In its eighteenth-century form it is traceable to a debate that started with the Reformation but took a recognizably modern shape only in the seventeenth century. That reason and experience offer a route to some degree of religious belief or knowledge has been a common assumption for as long as philosophy has served the interests of the Church, the Synagogue, or the Mosque; but historically it was a route that was not sharply differentiated from revelation. The evidence of the world was one kind of revelation and that of conscience another. Verbal revelation as a third kind has always had an important role in institutional religion. Different modes of revelation suited the knowledge and mental capacities of different believers and were considered compatible.

In the eyes of the Reformers, however, the institutions of religion had become corrupted over the centuries and had corrupted in turn both the spirit and the letter of the message they purported to preserve. The Catholic Church took refuge in the longevity and solidity of its tradition, including a continuity of biblical and doctrinal interpretation and of what were taken to be miraculous occurrences that identified it uniquely with the original Church from the days of the Apostles. Protestants sought to discredit Catholic miracles while safeguarding those of the Bible and to portray themselves as the rediscoverers and true heirs of the first Church. In this contest, the nature and basis of institutional authority and historical evidence, and the role of reason in general and individual reason in particular, were all up for review.