Athanasius was the young assistant to the Alexandrian bishop Alexander. During Athanasius’ 45 years of service as archbishop and patriarch, approximately 1/3 of this time was spent in forced exile because of his steadfast defense of the key terminology of the Nicene Creed. In 332 Constantine, who had begun to change sides due to the pressure of other bishops, restored Arius as a presbyter in Alexandria and ordered the new bishop, Athanasius, to accept him back into communion. Athanasius refused unless Arius would affirm homoousios, which means “of the same substance”, as describing the relation between Father and Son. Arius would not. Athanasius continued to reject him and ignored the emperor and because of this he was exiled to Trier. He is known within Church history as the saint of stubborness for his unwillingness to compromise of the full deity of Jesus Christ.
After Constantine died, his son Constantius took over and he insisted in changing the homoousios with homoiousios. The difference between homoousios and homoiousios is the difference between the divine and the creaturely. One says that the Son is God. The other says that the Son is like God. In a non-ecumenical synod in Alexandria, Athanasius proposed and the synod accepted an explanatory statement that declared the Father, Son, and Holy Spirit to be three distinct but not separate hypostases of the one God. The purpose of putting forth this new idea was to contradict Sabellian Modalism by making clear that the Father, Son, and Holy Spirit, though one substance (homoousios), are not the same identical person or subsistence. They are three distinct persons (hypostases) and not merely three masks or manifestations or aspects of the one personal God, as Sabellianism averred.
–On the Incarnation of the Word– probably written in his first exile in Trier, it is a book about the necessity of a real incarnation of God in humanity for human salvation and stresses the deity of Jesus Christ. One of his main aims in the work was to make clear that the Son is begotten but not made. His Christology is strongly reminiscent of Origen’s work. He has been considered a “right-wing Origenist”.
–Against the Arians– It was written between 356-360, a time when the Arian heresy under the guise of semi-Arianism was about to become the enforced orthodoxy for the entire church. Here he is deconstructing radical subordinationism. The main message is that “the Logos is not a creature but is of one substance with the Father,…because only so is our salvation fully realized and guaranteed.
–Conclusion: It should be clear, then, why Athanasius stubbornly refused to compromise on the terminology for the relationship of the Son to the Father. “What is at stake is not just a theological theory but people’s salvation.” He laid the foundation and others—namely, the Cappadocian fathers—built on it. He is quoted as saying “Jesus whom I know as my Redeemer cannot be less than God.”