The monastery of St. Thaddeus (also known as the Qara Kelisa) is located in the province of West Azerbaijan, 20 km from the southwest of Maku City, in proximity to a village with the same name. Some scholars believe this monastery is the first Christian building in the world; it is said that Thaddeus was one of the apostles of Jesus Christ who was invited to Armenia in 40 AD. He came to Armenia to preach Christianity.
Among those who changed their religion to Christianity were Sanatrok, king of Armenia, and his daughter Santukhd. However, the king regretted and opposed the new religion. But his efforts to change his daughter's new religion were in vain, and he finally ordered the assassination of Thaddeus and his daughter, Santukhd, and other Christian groups.
In 302 AD, during the reign of Tiridates (one of the kings of Armenia), Christianity became the state religion in Armenia. The Christians, who have preserved the memory of the martyrdom of Thaddeus and Santukhd from generation to generation, built monasteries in their mausoleum, which Qara Kelisa is one of them.
Qara Kelisa or St. Thaddeus Apostle Monastery has been damaged (earthquake, looting, and so on) and loveness for many centuries, and it also has periods of prosperity and glory. Today, the building has attracted the global attention of Christians across the world for its ritual ceremony. These ritual ceremonies have been performed for more than half a century.
Pilgrimage to the Qara Kelisa is one of the seasonal celebrations. It is held in public with rituals and religious ceremonies. The time of the celebration of Qara Kelisa cannot be determined according to the Solar Hijri calendar (Persian calendar); because this ceremony, like most Armenian holidays, is related to Armenian religious and national events. It is held for three days, almost during the last two weeks of July (Thursday, Friday, and Saturday).
The Iranian-Armenians go to Qara Kelisa from the cities of Tabriz, Urmia, Tehran, and Isfahan, as well as Christians in Armenia and other parts of the world. They visit Qara kelisa to take part in the celebration and pilgrimage for a few days. In addition to the Armenians, Assyrian families and some Catholic families also attend the ceremony.
Baptism of infants and children, the wedding ceremony, the lighting of candles, and the ringing of church bells, are performed during these three days. The Cathedral of St. Thaddeus, along with the Dzordzor Chapel, the church of St. Astvatsatsin, and St. Thaddeus Apostle Monastery, are inscribed on the World Heritage List.