The aim of the paper is to apprehend the early concept of rationality in
reformed epistemology, which belongs to within the tradition of analytic
philosophy. In order to do it, we will first look into the historical situation of
American Philosophical society which reformed epistemology appeared. and then
we will deal with two philosophical views claims that theistic beliefs are
irrational -namely, evidentialism and classical foundationalism. we respectively
investigate the concept 'rationality' of evidentialism and classical foundationalism
and its hidden assumption, after apprehending what each view stand for. After
that, we can arrive at a different concept of rationality which early Reformed
epistemologists support in order to defend the claim that the theistic beliefs are
rational, against those two philosophical views.