Catholicos of All Armenians Gosdantin (Constantine) I’s long tenure, one of the longest in the history of the Catholicoi of the Armenian Church, was marked by complex historical issues.
The son of a certain Vahram, probably born in the 1180s, Gosdantin of Partzerpert or Mavrian was educated in the monastery of Mlij, near Tarsus (Cilicia), which was a renowned center of manuscript copying, and then in the fortress of Hromkla, the seat of the Catholicosate of All Armenians from 1203-1292.
The Kingdom of Cilicia was in turmoil after the death of King Levon I in 1219. His daughter Zabel, who was four at the time of his death, was the heir of the throne, under the regency of the powerful prince Gosdantin the Bailiff (son of Levon’s maternal uncle). To add more complications, in 1221 Hovhannes VI of Sis passed away. Although Gosdantin of Partzerpert was an ecclesiastic deserving such honor, according to the historians, it appears that the regent suggested or handpicked his namesake as successor to the late Catholicos. He is said to have been the bishop of Mlij, which was a monastery and not a diocese, and thus it is likely, according to Maghakia Ormanian, that he was the bishop of Partzerpert.
The marriage of Zabel to prince Philippe of Antioch in 1222 ended in a failure, since the Latinophile policy of the Catholic prince alienated him from the nobility, and the next year Philippe was imprisoned. He died in prison in 1225 or 1226, and Gosdantin the Bailiff decided to marry Zabel to his own son Hetum. Catholicos Gosdantin I married them, both aged eleven, in 1226. In 1252 he would preside over her funeral procession.
In the 1220s, during the first years of his pontificate, the construction of St. Sophia, the royal church of Sis, the capital of Cilicia, was finished. Gosdantin I led a policy tending to maintain the independence of the Armenian Church. Catholicos Gosdantin I was also a man of culture. He opened new schools, founded congregations, and encouraged the production of manuscripts, including works by famous miniaturist Toros Roslin. After 1236, Greater Armenia fell under Mongol domination. In 1242 the Catholicos participated in the first negotiations of the Cilician kingdom with the Mongols. In 1247 the Catholicos sent archimandrite Teotos to the local Mongol general and obtained his agreement to rebuild the monastery of St. Thaddeus in the region of Artaz and found a congregation.
Meanwhile, the situation of the church in Cilicia led Gosdantin to gather an assembly of Cilician bishops in 1243. The ecclesiastic assembly was held in Sis, but the representatives from Greater Armenia were not invited. The assembly approved rules for consecrations, priesthood, moral issues, and so on and so forth.The Catholicos could not accomplish his project of going to Armenia himself and obtaining the agreement of local ecclesiastics. In 1246 he sent historian Vartan Areveltsi to Greater Armenia with such a mission.
In 1254 archimandrite Hagop Klayetsi represented the Catholicos in negotiations with Byzantine emperor John Vadakes and Greek Orthodox Patriarch Manuel aimed at establishing a temporary reconciliation between Cilicia and Byzantium. In the 1260s Gosdantin I engaged in heated controversies with the papal legate in Cilicia and Pope Clement IV himself over doctrinal issues.
After a forty-six year reign, Catholicos Gosdantin I passed away in Hromkla on May 9, 1267, where he was buried. He was succeeded by Catholicos Hagop I Klayetsi.