St. Mark was the Archbishop of Ephesus at the time when the Byzantine Emperor John VIII Palaeologus sought military help from the Western lands to defend the remnant of the East Roman Empire from the invading Moslem armies. Because of this desire to seek military help, the Emperor and most of the bishops from the East were willing to compromise the ancient traditions of the Church as regards to the innovative and incorrect Western teaching about purgatory, the primacy and rulership of the office of the Bishop of Rome, and the change of the Nicean Creed without the whole church present to approve of adding the word “filioque.”
A council in the West was called first in Basel, then transferred to Ferrata, then transferred to Florence, where at last the Eastern Emperor and many of his court and bishops came. All the bishops except St. Mark compromised the faith and traditions and signed for church unity, but when they returned to Constantinople the people soundly rejected this council as false and would not agree to this compromise of their faith. St. Mark, the “Pillar of Orthodoxy,” died peacefully in 1445. Faith is never compromise.