Callistus I of Constantinople was a 14th-century Byzantine prelate and monk who served as the Ecumenical Patriarch of Constantinople during two separate terms between 1350 and 1363. A dedicated follower of Gregory Palamas, he spent twenty-eight years living as a monk on Mount Athos. He is remembered for his significant role in establishing the orthodoxy of Hesychasm through a major synod in 1351. As a theologian and writer, he contributed to the spiritual traditions of the Eastern Orthodox Church through his ascetic writings.
Ecclesiastical career
After being elected patriarch in 1350, Callistus worked to spread Palamite doctrine across various jurisdictions. He was briefly deposed in 1353 for refusing to participate in the coronation of the emperor's son, but he returned to the throne in 1354. During his second term, he reorganized the patriarchal administration and parish systems. He also maintained strict ecclesiastical authority, notably excommunicating Stefan Dušan for declaring the Serbian archbishop an independent patriarch.
Literary works
As a scholar and writer, Callistus authored a hagiography regarding his teacher, Gregory of Sinai. He also co-authored the Century, a significant treatise on hesychastic ascetic practices written with his friend Ignatius Xanthopoulos. This work was later included in the Philokalia, profoundly influencing Orthodox spiritual life. His writings often focused on the practical methods used by monastics to achieve spiritual union with God.
Death
In August 1363, Callistus died while traveling to Serbia as part of an imperial embassy seeking assistance against the Ottoman Empire. He passed away before he could return to Constantinople. His death occurred during a journey that followed a meeting with Maximos of Kafsokalyvia, who reportedly offered a prophetic farewell to the patriarch while he was passing through Mount Athos.