This paper deals with the relevance of the method as a guide for obtaining knowledge within the sphere of the Science of Religion, as well as the significance that the first rule of the Cartesian method had for the constitution of a scientific-religious programme. The aim is to analyse and draw up a dialogue between the first rule of the Cartesian method and the concept of method used by the Science of Religion, showing that the discoveries made by this science can carry with them traces and influences of this rule, which was built even before the establishment of an academic area focused on religious knowledge.