Hieromartyr Gregory was the son of a relative of the king of Armenia and lived in the time of the pagan emperor Diocletian. He was catechized in the Christian faith and then embraced it by receiving the Holy Baptism in Caesarea, Cappadocia. After being ordained a Presbyter, he went to Armenia to spread the Holy Gospel.
In Armenia, his relative tried to persuade him to make sacrifices to idols and return to his native religion. Gregory’s negative attitude angered the pagan ruler, who insulted him and led him to torture. Despite the hardships he suffered, he remained steadfast in the faith in the Savior Christ and the Orthodox faith.
After many miraculous events, the pagan ruler repented of his previous life and asked for God’s grace. After being catechized, he was baptized in the name of The Holy Triune God.
The entry of the Armenian ruler into the Church led many of his compatriots to the path of true faith. The fervent faith of the clergy, the steadfastness of words and deeds as much as possible in their lives and the courageous Christian confession contribute on the one hand to the spread and consolidation of the holy Gospel in the world and on the other to the real social prosperity of God’s people.
Source: Church of Cyprus
https://orthodoxtimes.com/memory-of-saint-hieromartyr-gregory-the-illuminator-of-greater-armenia-2/