These doctrinal issues center around the Orthodox perception that the Catholic theologians lack the actual experience of God called "theoria" and thereby fail to understand the importance of the heart as a noetic or intuitive faculty. It is what they consider to be the Catholic Church's reliance on pagan metaphysical philosophy and rational methods such as scholasticism rather than on the intuitive experience of God (theoria) that causes Orthodox to consider the Catholic Church heretical. Other points of doctrinal difference include a difference regarding human nature as well as a difference regarding original sin, purgatory, and the nature of Hell.