The Saint Whose Father was a Bishop

St. Gregory of Nazianzus's father also named Gregory, was converted to the Christian faith from the monotheistic sect known as the Hypsistarii under the influence of his Christian wife. He was soon afterward consecrated bishop of his native city, Nazianzus (the exact location of which is not known), by bishops on their way to the Council of Nicaea in 325.

After six years in Athens studying rhetoric, poetry, geometry, and astronomy Saint Gregory returned to his parents at Nazianzus. At thirty-three years of age. against his will, Saint Gregory was ordained to the holy priesthood by his father. 

After the death of the Arian Emperor Valens, Gregory was asked to go to Constantinople to preach there. For thirty years, the city had been controlled by Arians or pagans, and the orthodox did not even have a church there. Gregory went. He converted his own house there into a church and held services in it. There he preached the Five Theological Orations for which he is best known, a series of five sermons on the Trinity and in defense of the deity of Christ. People flocked to hear him preach, and the city was largely won over to the Athanasian (Trinitarian, catholic, orthodox) position by his powers of persuasion. The following year, he was consecrated bishop of Constantinople. He presided at the Council of Constantinple in 381, which confirmed the Athanasian position of the earlier Council of Nicea in 325. Having accomplished what he believed to be his mission at Constantinople, and heartily sick of ecclesiastical politics, Gregory resigned and retired to his home town of Nazianzus, where he died in 389. His last days were spent in solitude and austerity. He wrote religious poetry, some of it autobiographical, of great depth and beauty. He was acclaimed simply as “the Theologian.” 

Gregory's most significant theological contributions arose from his defense of the Nicene doctrine of the Trinity. In contrast to the Arian and Apollonarian heresies common in his day,[45] he emphasized that Jesus did not cease to be God when he became a man, nor did he lose any of his divine attributes when he took on human nature. Conversely, Gregory also asserted that Christ was fully human, including a full human soul.

References
https://www.britannica.com/biography/Saint-Gregory-of-Nazianzus

https://www.oca.org/saints/lives/2022/01/25/100298-saint-gregory-the-theologian-archbishop-of-constantinople

https://www.franciscanmedia.org/saint-of-the-day/saint-gregory-nazianzen

http://justus.anglican.org/resources/bio/155.html

https://www.newworldencyclopedia.org/entry/Gregory_of_Nazianzus