Saint Gregory the Theologian (326-389) was the son of Gregory (later Bishop of Nazianzus) and Nonna, a woman of high moral principles. Even before the birth of her son, she promised to dedicate him to God and used all her efforts to bend his will to the service of the Lord. St. Gregory considered the upbringing given to him by his mother to be the most important thing for himself. 
With his outstanding abilities, St. Gregory received an excellent education: he studied in the schools of Caesarea in Palestine, where there was a rich library collected by the martyr Pamphilus, in Alexandria, where he studied the works of Origen, and finally in Athens, where he became particularly close to St. Basil the Great, with whom he had known a little earlier and considered friendship with whom more useful than the highest school. The holy friends in Athens had one room, one way of life; they were familiar with only two roads: one led to the temple of God, the other to the college. In Athens, St. Gregory met Julian, nicknamed "The Apostate," who, after becoming emperor, renounced Christianity and tried to revive paganism in the Roman Empire (361-363) and left a vivid image of this evil and treacherous enemy of the Church. At the age of 26, St. Gregory was baptized.
After returning to his homeland, St. Gregory avoided holding any public office for a long time. Thinking about God, praying, reading the word of God, writing inspired words and songs, and ministering to elderly parents were his activities. He spent some time with his friend Vasily in his desert and considered this time the happiest in his life. His father, who was already a bishop, in need of an assistant, called him from the Vasilyeva desert to Nazianzus and ordained him a presbyter. Even this rank so intimidated Gregory by the height and weight of the duties associated with it that he retired to the solitude of the desert. Having calmed the agitation of his spirit there, he returned to his father and took up the priestly ministry, comforted that he, by serving God, was also helping his elderly parent in his care of the flock.
Meanwhile, his friend, Basil the Great, had already reached the high rank of archbishop. Desiring to have a devoted and enlightened assistant in the administration of a vast area, St. Basil offered Gregory the position of chief protopresbyter in his department, but St. Gregory declined to accept this honorable and influential position. Some time after that, Gregory was consecrated bishop of the city of Sashima by a secret agreement between Archbishop Basil and Gregory's father. Seeing the will of God in this, he accepted holy ordination, but refused to accept the position itself and continued to serve his parent and the flock of Nazianzus as a co-ruler (vicar). In 374, Gregory's elderly parent died, followed by his mother. Saint Gregory continued his father's work on the management of the Nazianzus Church for some time, but he became very ill. After recovering, he retired to a secluded monastery, where he remained in fasting and prayer for about three years.
But the great lamp could not hide in a monastic cell. Elected by the Orthodox bishops and laity to the see of Archbishop in Constantinople, he arrived there during the era of the strongest rule of the Arians, when they seized all the churches in the capital. St. Gregory stayed at the house of his acquaintances. He turned one of the rooms into a temple, calling it "Anastasia", which means "resurrection", with the hope that Orthodoxy would be resurrected here, and began to preach. The Arians bombarded him with taunts and curses, threw stones at him, and sent secret assassins to him. 
With his strong word, example of his life, and pastoral zeal, he defeated the enemies of the Church. People flocked in great numbers from all over to listen to his inspired sermons. Every day thousands of people returned from heresy to the Orthodox Church.
Finally, after the reign of the Orthodox Emperor Theodosius (379-395), the stubborn Arians were expelled from the temples of the capital. When the Macedonian heresy was discovered (Macedonius denied the Divinity of the Holy Spirit), Saint Gregory fought against it and took a lively part in the meetings of the Second Ecumenical Council. Having accomplished his feat, he retired to his native village of Arianz, near Nazianzus, and here he spent the last years of his life in strict ascetic labors.
The relics of St. Gregory the Theologian are located in the village of Nea Karvali in the church of St. Gregory. This place is located near the town of Kavala in the Greek province of Macedonia.
For his remarkable theological works, St. Gregory received from the Church the honorary title of Theologian and universal teacher, and for his ability to penetrate into the deepest mysteries of faith with thought and express its incomprehensible truths with transparent clarity and strict precision, the Church in one of the prayers calls him the highest mind. 
For a long time there was a debate in Constantinople about which of the three hierarchs should be given preference. One part of the people praised St. Basil (January 1), another stood for Gregory the Theologian (January 25), and the third revered St. John Chrysostom (November 13).
This led to ecclesiastical strife among Christians: some called themselves Basilians, others Gregorians, and others Johannites.
By God's will, in 1084, three hierarchs appeared to Metropolitan John of Evkha and, declaring that they were equal before God, ordered them to stop arguing and establish a common day for celebrating their memory.