God the Father makes us firm in Christ and establishes in all souls a faith that is correct and unshakable in holding that Christ is God by nature and in truth.

That is so even if he was visibly in a form like ours, being born from a woman according to human nature and yet being above every created thing.

[...] It is God, therefore, who makes us firm in Christ, God who seals and anoints us and gives the Spirit as the guarantee, so that we might know that the Son is not ‘yes’ and ‘no’ but, rather, is truly God and that the ‘yes’ to all good things is in him.

God is said to seal and to anoint us, giving the guarantee of the Spirit, so that Christ might be the one who fulfils these things in us, not in a servile way nor as one anointing and sealing us with an alien spirit, but with the Spirit which is his own and the Father’s.

For the Holy Spirit is in both Father and Son by means of the identity of nature, not as something shared between them but rather as coming forth from the Father through the Son to the created universe.

Christ breathed on the holy Apostles and said Receive the Holy Spirit, and it is through him and in him that we have received the impress of the divine and intelligible image.

For the divine Apostle himself said in his letter to the Galatians, My children, with whom I am again suffering labour pains until such time as Christ is formed in you.

Now if we are conformed to Christ, and if we are enriched by the divine image within us, then Christ himself is the image of God the Father, and his exact resemblance, and we are called to his likeness, not by means of a participation in holiness but rather in nature and essence.

For it is not unreasonable that the one [i.e. the Christian] who, by [human] nature, is related to him [Christ] who is true God by [divine] nature and who is generated from his substance should himself be divine.

He has been sealed by God the Father, as John the wise says, He who receives his witness has put his seal to the fact that God is true.

But he has not been sealed in the same way as we have, for the Father reveals that he himself is wholly in the nature of the Son, which is not true for us.

Thus Christ says, He who has seen me has seen the Father.

Cyril of Alexandria (c. 376-444): Commentary on 2 Corinthians (PG 74:921-3), from the Monastic Office of Vigils, Monday of the 7th Week in Ordinary Time, Year 2.