Mark of Ephesus
Our father among the saints Mark of Ephesus (Greek: Μάρκος Ευγενικός), Archbishop of Ephesus, was famous for his courageous defense of Orthodoxy at the Council of Florence (1439 A.D.) in spite of the Byznatine emperor John VIII Palaeologus and the pope of Rome Eugenius IV. He held Rome to be in schism and heresy for its acceptance of the Filioque clause added to the Nicene-Constantinopolitan Creed and for the claims of the papacy to universal jurisdiction over the Church, and was thus the only Eastern bishop to refuse to sign the decrees of the council. Sometimes he is called "The conscience of Orthodoxy".
He died peacefully in the year 1444 A.D. On his death bed, Mark implored Gregory, his disciple, and later Patriarch Gennadius II of Constantinople, to be careful of the snares of the West and to defend Orthodoxy.
For his efforts at the Council of Florence and his defense against: 1- the addition of the Filioque, 2- the primacy of the Pope, 3-purgatorial fire purification; the Orthodox Church considers him a saint, calling him a Pillar of Orthodoxy. His feast day is January 19.
"It is impossible to recall peace without dissolving the cause of the schism—the primacy of the Pope exalting himself equal to God." 
"The Latins are not only schismatics but heretics... we did not separate from them for any other reason other than the fact that they are heretics. This is precisely why we must not unite with them unless they dismiss the addition from the Creed filioque and confess the Creed as we do." 
"Our Head, Christ our God... does not tolerate that the bond of love be taken from us entirely." 
"We seek and we pray for our return to that time when, being united, we spoke the same things and there was no schism between us." 
"The Symbol of the Faith must be preserved inviolate, as at its origin. Since all the holy doctors of the Church, all the Councils and all the Scriptures put us on our guard against heterodoxy, how dare I, in spite of these authorities, follow those who urge us to unity in a deceitful semblance of union—those who have corrupted the holy and divine Symbol of Faith and brought in the Son as second cause of the Holy Spirit" (s.v. Jan 19th in The Synaxarion, ed. Hieromonk Makarios of Simonas Petra, and trans. Christopher Hookway; Ormylia: Holy Convent of The Annunciation of Our Lady, 2001).
"The souls of the departed can indeed benefit to their 'advancement,' and even the damned to a relative 'relief' of their lot, thanks to the prayers of the Church and through the infinite mercy of God; but the notion of a punishment prior to the Last Judgment and of a purification through a material fire is altogether foreign to the tradition of the Church" (ibid.).
Death, Miracle and Canonization
He died peacefully at the age of 52 on June 23, 1444, after an excruciating two week battle with intestinal illness. On his death bed, Mark implored Georgios Scholarios, his former pupil, who later became Patriarch Gennadius of Constantinople, to be careful of the snares of the West and to defend Orthodoxy. According to his brother John, his last words were "Jesus Christ, Son of the Living God, into Thy hands I commit my spirit." Mark was buried in the Mangana Monastery in Constantinople.
There is an account of a posthumous miracle performed by St. Mark of Ephesus. Doctors gave up on trying to save the life of the terminally ill sister of Demetrios Zourbaios, after their efforts had worsened her condition. After losing consciousness for three days she suddenly woke up to the delight of her brother, who asked her why she woke up drenched in water. She related that a bishop escorted her to a fountain and washed her and told her, "Return now; you no longer have any illness." She asked him who he was and he informed her, "I am the Metropolitan of Ephesus, Mark Eugenikos." After being miraculously healed, she made an icon of St. Mark and lived devoutly for another 15 years.
In 1734 the Holy Synod of the Church of Constantinople under Patriarch Seraphim I canonized Mark of Ephesus as a saint, stating:
"All of us of the holy Eastern Church of Christ acknowledge the holy Mark Evgenikos of Ephesus. We honor and receive this saintly, God-bearing and righteous man as a zealot of ardent piety, who was a champion of all our sacred dogmas and correct piety. He is an emulator and equal to the holy theologians, and those that adorned the Church of ancient times."
Troparion (Tone 4)
- By your profession of faith, O all-praised Mark
- The Church has found you to be a zealot for truth.
- You fought for the teaching of the Fathers;
- You cast down the darkness of boastful pride.
- Intercede with Christ God to grant forgiveness to those who honor you!
Kontakion (Tone 3)
- Clothed with invincible armor, O blessed one,
- You cast down rebellious pride,
- You served as the instrument of the Comforter,
- And shone forth as the champion of Orthodoxy.
- Therefore we cry to you: "Rejoice, Mark, the boast of the Orthodox!"