The debate surrounding the epistemic status of Christian beliefs is as old as Christianity itself: Do Christian beliefs have a rational background?In this volume Ralf-Thomas Klein studies one particular and very influential contribution to this matter: the works of the American philosopher Alvin Plantinga (born 1932), a prominent representative of the so-called Reformed Epistemology. Klein reviews the three developmental phases in Plantinga´s approach and studies each of them exhaustively. The focal point lies on Plantinga´s third main thesis concerning knowledge and Christian beliefs. Klein extends this approach and develops his own suggestions for a revised Aquinas/Calvin model.