He died peacefully in the year 1444 A.D. On his deathbed, 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: the addition of the Filioque, the primacy of the Pope, and purgatorial fire purification, the Orthodox Church considers him a saint, calling him a Pillar of Orthodoxy. His feast day is January 19.