Today is the joint Feast of St Cyril (+444) and St Athanasius (+373), Patriarchs of Alexandria.
St Athanasius stood firm against Arius, who denied that the Son of God is truly God. Later, St Cyril led the opposition to Nestorius, who would go no further than to say that Jesus was a man conjoined in perfect harmony of will with God.
Such teachings, St Cyril realised, would leave the Eucharist an empty, lifeless ritual.
AND as the Body of the Word Himself is Life-giving, He having made it His own by a true union passing understanding and language; so we too who partake of His holy Flesh and Blood, are quickened in all respects and wholly, the Word dwelling in us Divinely through the Holy Ghost, humanly again through His Holy Flesh and Precious Blood.
The most holy Paul will confirm the truth of what I said, writing thus to those in Corinth who believed in our Lord Jesus Christ, I speak as to wise men, judge ye what I say, the Cup of Blessing which we bless is it not the communion of the Blood of Christ? the Bread which we break is it not the communion of the Body of Christ? for one bread one body are we who are many, for we all are partakers of One Bread.
For having partaken of the Holy Ghost, we are made one both with Christ Himself the Saviour of all and with one another: we are of the same body in this way, that we being many are one bread one body, for we all are partakers of the One Bread. For the Body of Christ which is in us binds us together into unity and is in no way divided.
But that through the Body of Christ we have been brought together into unity with Him and with one another, the blessed Paul will confirm, writing, For this cause I Paul the Prisoner of Jesus Christ in behalf of you Gentiles, if ye heard of the economy of the grace of God which was given me to you-ward, how that by revelation He made known unto me the mystery, as I wrote afore in few words, whereby when ye read, ye may understand my knowledge in the mystery of Christ which in other ages was not made known to the sons of men as now it is revealed unto His holy Apostles and prophets in the Spirit, that the Gentiles should be fellow-heirs and of the same body and co-participant in the promise in Christ.
St Cyril of Alexandria, “Against Nestorius”, Book 4. Translation from CCEL.
Apolytikion. Tone 3.
SHINING forth with works of Orthodoxy, ye quenched every false belief and teaching and became trophy-bearers and conquerors. And since ye made all things rich and with true piety, greatly adorning the Church with magnificence, Athanasius and wise Cyril, ye both have worthily found Christ God, Who doth grant great mercy unto all.