What is the significance of St. Athanasius’s work Against the Heathen and The Incarnation of the Word of God?

St. Athanasius’s work Against the Heathen and The Incarnation of the Word of God (c. 335) is a two-part work of apologetics that was the first great classic of developed Greek Orthodox theology. It emphasized that Jesus, as the Son of God and the eternal Word through whom God made the world, entered the world in human form to lead humans back to the harmony from which they had fallen away. In the work, Athanasius reacted vigorously against the 4th-century heresy of Arianism, for which the Son was regarded as a lesser being, and he welcomed the definition of the Son that was formulated at the First Council of Nicaea in 325: as “consubstantial with the Father.”