Equal-to-the-Apostles Hieromartyr Cosmas, in the world Constantine, was from Aetolia. He studied first in his homeland under the guidance of Archdeacon Ananias Dervishan, and then completed his education on Mount Athos, at the Vatopedi College under such famous teachers at that time as Nikolai Tsartsulia (from Mezova) and Evgeny Bulgaris (later, in 1775-1779, Archbishop of Yekaterinoslav and Kherson).
Remaining on Mount Athos in the Filofeevskaya monastery to succeed in spiritual labors, he was tonsured a monk there with the name Kosma, and then ordained a hieromonk. The desire to guide the Christian brothers to the path of salvation and strengthen them in the faith prompted Saint Cosmas to ask for the blessing of the spiritual fathers and leave for Constantinople. There he mastered the art of eloquence and, having received written permission from Patriarch Seraphim II (and later from his successor Sophronius) to preach the Holy Gospel, began to proclaim it first in the churches of Constantinople and the surrounding villages, then in the Danubian principalities, in Thessalonica, in Verria, in Macedonia, in the regions of Himara, Acarnania, Aetolia, on the islands of St. Mavra, Kefalonia and other places. His preaching, filled with the grace of the Holy Spirit, simple, calm and meek, brought great spiritual benefits to Christians. Like His holy apostles, the Lord Himself helped him and confirmed his word with signs and wonders. Preaching in Albania, in those remote places where Christian piety was almost lost, among savage and calloused people, hardened in sins, Saint Cosmas led them by the Word of God to sincere repentance and correction.
On his instructions, church schools were opened in the villages. The rich donated their funds for the improvement of churches, for the purchase of sacred books (which the saint distributed to the literate), veils (which he gave to women, exhorting them to walk with their heads covered), rosaries and crosses (which he distributed to the common people). Since the churches could not accommodate everyone who wanted to listen to the wise preacher, Saint Cosmas and a council of priests held vigils in the fields and squares, where thousands of people prayed for the living and the dead and were edified by his teachings. And wherever Saint Cosmas stopped and preached his sermon, grateful listeners erected large wooden crosses, which remained forever in memory of this.
The apostolic ministry of Saint Cosmas ended with his martyrdom in 1779. At the age of 65, according to the slander of the Jews, he was betrayed to the Turks and strangled. His body was thrown into a river, and three days later was found by priest Mark and buried near the village of Kalikontasi in the Ardevuz Monastery of the Entry into the Temple of the Most Holy Theotokos. Subsequently, the relics of the holy martyr were transferred to various places for blessing.