Prior to the twentieth century, it was usually assumed that revelation was received in two modes. "Special" revelation represented communication of knowledge about God through supernatural agency. "General" revelation consisted of what could be known of God through either abstract philosophy or reflection on the nature of the universe.

Twentieth-century challenges

In the twentieth century, however, there were strong challenges both to the concept of revelation as disclosure of propositional knowledge and to the validity of a "natural theology" based on general revelation. The work of the Swiss Protestant theologian Karl Barth (1886–1968), in particular, had led, by the middle of the century, to both a new emphasis on the centrality of special revelation for theological thinking and a perspective in which theological propositions represented no more than...