(c. 329–89), with Saints Athanasius, Basil, and John Chrysostom, a Father of the Church and one of the four Eastern Doctors of the Church. Called Gregorius Theologus (Gr., “Gregory the Theologian”), he was born near Nazianzus, in Cappadocia (now Turkey), and educated in Alexandria and Athens. He was baptized in 360 by his father, who was bishop of Nazianzus. Deciding to pursue a life of devotion, he went to Pontus, where he lived in the desert near the Iris River (now the Ye[scedil]il Irmak River in Turkey) with St. Basil. The two men compiled an anthology of the writings of the Christian teacher and theologian Origen, called the Philokalia (Gr., “Love of the Beautiful”). As bishop of Caesarea, Basil pressured Gregory in 371 or 372 to accept the see of Sasima, a small village in Cappadocia. Gregory disliked public life, however, and retired until his father's death in 374.

In 378 or 379 Gregory took charge of the Nicene congregation of Constantinople. There he delivered five discourses on the Trinity that earned him fame as The Theologian. He was appointed bishop, but retired because of resistance from the Arians. To prevent further schism, he returned to Nazianzus, where he remained until his death. His feast day is January 2 in the Roman Catholic church and January 25 in the Orthodox church. His surviving works comprise about 45 sermons, 243 letters, and 407 dogmatic and moral poems.