John XIV of Constantinople
John XIV, surnamed Kalekas, was the Ecumenical Patriarch of Constantinople from 1334 to 1347. He was an anti-hesychast and opponent of Gregory Palamas. He was an active participant in the Byzantine civil war of 1341–1347 as a member of the regency for John V Palaiologos, against John VI Kantakouzenos.
Seal of John XIV Kalekas
Gregory Palamas was a Byzantine Greek theologian and Eastern Orthodox cleric of the late Byzantine period. A monk of Mount Athos and later archbishop of Thessaloniki, he is famous for his defense of hesychast spirituality, the uncreated character of the light of the Transfiguration, and the distinction between God's essence and energies. His teaching unfolded over the course of three major controversies, (1) with the Italo-Greek Barlaam between 1336 and 1341, (2) with the monk Gregory Akindynos between 1341 and 1347, and (3) with the philosopher Gregoras, from 1348 to 1355. His theological contributions are sometimes referred to as Palamism, and his followers as Palamites.
Painting of Saint Gregory in Monastery of Vatopaidi, Mount Athos, Greece by Manuel Panselinos. The captions call him, among other titles, Νέος Χρυσόστομος: A New Chrysostom.
Church of Saint Gregory Palamas housing his relics, in Thessaloniki (architect: Ernst Ziller)
Interior of the Church of St. Gregory Palamas in Thessaloniki
The reliquary of St. Gregory Palamas