Saint Callistus I of Constantinople

Callistus I of Constantinople (Medieval Greek: Κάλλιστος; died August 1363) was the Ecumenical Patriarch of Constantinople for two periods from June 1350 to 1353 and from 1354 to 1363. Callistus I was an Athonite monk and supporter of Gregory Palamas. He died in Constantinople in August 1363. Nothing is known of Callistus' early life. He was a disciple of Gregory Palamas and Gregory of Sinai. He lived at Mount Athos for 28 years and was a monk at the Skete of Magoula near Philotheou Monastery at Mount Athos. In his "Hagiography of Gregory of Sinai", he mentions two devotees, Jakov of Serres and Romylos of Vidin, then living and writing in Serbia. He also founded the Monastery of Saint Mamas at Tenedos, a small island near the Dardanelles. Callistus was elected to the throne of the see of Constantinople on 10 June 1350, succeeding Isidore I of Constantinople. In 1351, he convened a synod in Constantinople that finally established the Orthodoxy of Hesychasm. Callistus I and the ecumenical patriarchs who succeeded him mounted a vigorous campaign to have the Palamite doctrine accepted by the other Eastern patriarchates as well as all the metropolitan sees under their jurisdiction. However, it took some time to overcome initial resistance to the doctrine. One example of resistance was the response of the Metropolitan of Kyiv who, upon receiving tomes from Kallistos that expounded the Palamist doctrine, rejected the new doctrine vehemently and composed a reply refuting it. According to Martin Jugie, contemporary historians depict Callistus I as a "doctrinaire and brutal man whose persecuting zeal it was necessary to restrain". In 1353, Callistus I refused to crown Matthew Kantakouzenos, son of emperor John VI Kantakouzenos, as emperor with his father and, as a result, was deposed. After his deposition, Callistus I returned to Mount Athos. In 1354, after John VI abdicated, Callistus I returned as patriarch.