On the other hand, the Antiochian teaching about Christ as the incarnate Word could lead to the opposite misunderstanding. namely, to the understanding of the Incarnation as the union of God the Word, who at the same time retained his divine nature, with a specific person, Jesus. Such a theology sees in Christ two persons—divine and human—and ultimately leads to Nestorianism.

Both traditions, Antiochian and Alexandrian, had the same reality in mind. The Evangelist John wrote in Greek, but his way of thinking was Semitic. Therefore, when he used the Greek word "flesh," which has such a material connotation to the Greek listener, he was of course referring to the Hebrew meaning of the word (basar), which encompasses the entire living reality of human existence, both material and spiritual. It is in this sense that St. Athanasius also used the word "flesh." He saw in Christ one Person – the Divine Word, which took on not a separate human person, but human nature. Long before the Council of Ephesus, which confirmed the dogma of the Mother of God, Athanasius called the Virgin Mary the Mother of God. He attributed all the actions of the Savior to God the Word, as a single person. But in affirming the unity of Christ as the incarnate Word, Athanasius, like all Alexandrians, did not always feel that his terminology opened up the possibility of belittling the human nature of the Saviour, a danger that Apollinaris could not avoid.

Doctrine of the Trinity

The main merit of St. Athanasius lies in his struggle against Arianism. While there was not a single Orthodox bishop left in the Eastern Church, he courageously defended the Orthodox Nicene faith, which proclaimed the consubstantiality of the Father and the Son. As discussed above, this unbiblical term had a bad reputation and was condemned at the Council of Antioch in the third century as an expression of the modalistic heresy (if the essence is one, then there is no real difference between the Persons of the Holy Trinity: the Father, the Son, and the Holy Spirit are only different expressions (modes) of one and the same essence).

Athanasius did not go into theological subtleties. Fighting against Arianism for consubstantiality, he defended the very meaning, the very essence of Christianity. The Incarnation, death, and Resurrection of Christ brought salvation to the world. Denying the consubstantiality of Christ with the Father, Arianism threatened to destroy the very essence and foundation of the Christian faith: mankind needs salvation, but salvation is possible only from God, therefore Christ is both man and God, otherwise we are not saved. St. Athanasius firmly knew that only by defending the consubstantial faith could the purity of the Orthodox faith be preserved. He was not embarrassed by the fact that for this purpose it was necessary to introduce an unusual word that most theologians did not like. He considered any philosophical reasoning about the real meaning of this word unnecessary and even dangerous:

We should not inquire why the Word of God is not like ours, because, as has already been said, God is not like us. It is also unseemly to inquire how the Word is from God, or how He is God's radiance, or how God gives birth, and what is the image of God's birth. Whoever dares to undertake such investigations is mad, because he wishes to interpret in words what is ineffably inherent in God's nature and known only to God and His Son. This is the same as searching for where God is, why He is God, and what the Father is like. But just as it is impious and characteristic of those who do not know God, so it is impermissible to dare to make such inquiries about the birth of God's Son, and to measure God and His Wisdom by one's nature and one's weakness. For this reason, one should not imagine this contrary to the truth; and if anyone is perplexed during these investigations, he should not but believe what is written. It is better for those who are perplexed to be silent and believe, than not to believe because of perplexity.

(Against the Arians, 2, 36)

Athanasius speaks of the Holy Spirit in his letters to Serapion. His reasoning follows the same logic as his teaching about Christ. There is one God, the one-in-essence Trinity: the Father, the Son, and the Spirit. Like the Son, the Holy Spirit is also God, otherwise we are not saved:

... Of the Holy Spirit, God says that He is not just a Spirit, but His Spirit, and that by Him our spirit is renewed, just as the Psalmist says in the one hundred and third Psalm: "If you take away their spirit, they die and return to their dust. Thou shalt send Thy Spirit, and they shall be created, and Thou dost renew the face of the earth" (Psalm 103:29,30). If we are renewed by the Spirit of God, then it is not the Holy Spirit, but our spirit that is called created here. And if, on the basis that all things are brought into being by the Word, you admirably reason that the Son is not a creature, then is it not blasphemous to call the creature of the Spirit, by whom the Father through the Word brings all things to perfection and renews them?

(Serapion, Epistle 1:16,17)

Through the Holy Spirit, man's communion with God and deification take place. At the same time, the Spirit belongs to the Son, being His "own" (idios) Spirit: