“In the eighteenth century a new movement arose among intellectual Christians that came to be known as Deism or natural religion. These “enlightened” Christians insisted that all divine revelation—including Scripture—and especially the Great Tradition of Christian teaching and belief had to be judged by the canons of modern philosophical and scientific knowledge.
The British philosopher John Locke was a precursor of natural religion insofar as his book The Reasonableness of Christianity (1695) judged divine revelation itself by modern, secular standards of inquiry and knowledge. Locke’s Jesus was reduced to “The Messiah”—a kind of ethical prophet and spiritual leader who helped humanity rise to a newer and higher level. (Locke did not, however, deny any of the dogmas of Christianity. He simply neglected them.)
Deism and natural religion proper actually began with Locke’s disciple John Toland and then came to its purest form in Matthew Tyndal, both of whom argued that enlightenment reason must be the ultimate source and norm even for Christian belief. Other Deists and natural religionists who considered themselves Christians in some sense of the word included Thomas Jefferson and Benjamin Franklin.
In Europe a form of Deism and natural religion flourished among the intellectual elite and found organizational form in the Unitarian movement that began in London and spread to the United States in the last decade of the eighteenth century. The great German philosopher Immanuel Kant wrote Religion Within the Limits of Reason Alone (1793), which represents a deistic and natural religion approach to Christianity”
“The Mosaic of Christian Belief” by Roger Olson