Gregory the Illuminator was the apostle who brought Christianity to Armenia, converting King Tiridates III around 301 — making Armenia the first nation to adopt Christianity as its state religion, over a decade before Constantine's Edict of Milan. His story is inseparable from Armenian national identity: the Armenian Apostolic Church traces its founding to Gregory, and the title 'Illuminator' (Lusavorich) reflects the Armenian conviction that he brought the light of Christ to their nation. The historical core of his mission is reliable, though hagiographic tradition has been heavily embellished.

Traditionally, Gregory's thirteen years in Khor Virap were sustained by divine providence — a pious widow secretly brought him daily bread without anyone discovering her. His emergence from the pit, healthy and luminous, was taken as a miraculous sign. According to Agathangelos, Gregory had a vision in which Christ descended from heaven and struck the ground at Etchmiadzin with a golden hammer, marking the site of the mother cathedral.

According to the Armenian historian Agathangelos, Gregory was born the son of Anak, a Parthian nobleman who assassinated the Armenian king Khosrov II. The infant Gregory was smuggled out of Armenia and raised as a Christian in Caesarea in Cappadocia, where he was baptized and educated.

As an adult, Gregory returned to Armenia and entered the service of King Tiridates III, seeking to atone for his father's crime. When Gregory refused to offer sacrifice to the goddess Anahit, Tiridates subjected him to prolonged torture and eventually threw him into a pit — Khor Virap ('deep prison'), near Mount Ararat — where he languished for thirteen years, sustained by a widow's secret supply of bread.

Meanwhile, Tiridates was afflicted with a mysterious illness (tradition describes him being transformed into a wild boar) that no physician could cure. His sister dreamed that only Gregory could heal the king. Gregory was brought from the pit, healed Tiridates (through prayer, not medicine), and the king was converted. Armenia officially adopted Christianity around 301 — a century before most of the Christian world.

Gregory was consecrated bishop by Leontius of Caesarea and systematically destroyed pagan temples and built churches across Armenia. He established his see at Etchmiadzin, where the cathedral he founded remains the spiritual center of the Armenian Church. After organizing the church, he withdrew to a hermitage and died around 331.

• Bishop
• Missionary