Only three Orthodox saints wear the title Theologian
Gregory of Nazianzus, Cappadocian archbishop and Doctor of the Church, shaped how East and West speak about the Trinity. Orthodoxy ranks him with John the Apostle and Symeon the New Theologian as one of only three men officially styled "Theologian."
Gregory (c. 329–25 January 390) served as Archbishop of Constantinople and left a lasting mark on Trinitarian doctrine among Greek and Latin thinkers. Catholics count him a Doctor of the Church; Orthodoxy and Eastern Catholicism revere him among the Three Holy Hierarchs with Basil of Caesarea and John Chrysostom. The rare epithet "Theologian" sets him beside the Apostle John and Symeon the New Theologian. He held the see of Constantinople from 380 to 381.
Born to wealthy landowners Gregory the Elder and Nonna near Nazianzus in Cappadocia, he returned home in 361 and was ordained presbyter at his father's insistence, resenting the interruption of monastic hopes. When Emperor Julian turned publicly against Christianity, Gregory wrote Invectives Against Julian (362–363), arguing love and endurance would outlast flawed rulers. His father, a Hypsistarian whom Nonna converted in 325, had become bishop of Nazianzus in 328 or 329, and the son branded the forced ordination an act of tyranny.
He spent following years fighting Arianism's threat to divide Cappadocia, cooperating rhetorically with Basil after mediating with Bishop Eusebius of Caesarea. Later episcopal posts at Sasima and Nazianzus pulled him deeper into church politics, but his lasting fame rests on sermons and orations that taught Christians to speak carefully of Father, Son, and Spirit as one God in three persons. Basil consecrated him Bishop of Sasima in 372 chiefly to strengthen his own hand against Anthimus of Tyana, and Gregory soon refused to act as his friend's pawn. After both parents died in 374 he gave most of his inheritance to the needy, withdrew to a monastery at Seleukia from late 375 for three years, and in 379 answered the Antioch synod's call to win Constantinople for Nicene belief, turning a villa lent by his cousin Theodosia into a church he named Anastasia.
Source: Gregory of Nazianzus
