Karekin, born and baptized as Neshan Sarkissian, was born in the Armenian-populated village of
Kesab in northern
Syria, where he attended the Armenian elementary school. In 1946 he was admitted to the Theological Seminary of the Armenian Catholicosate of Cilicia and in 1949 ordained a deacon. In 1952, after having graduated with high honors, he was ordained a celibate priest and took the ecclesiastical name Karekin. He joined the order of the
Armenian Catholicosate of Cilicia. In 1955, he presented his doctoral thesis on the subject "The Theology of the Armenian Church, According to Liturgical Hymns Sharakans" and was promoted to the ecclesiastical degree of
vardapet (
archimandrite). In next year he served as a member of the faculty of the theological seminary in
Antelias,
Lebanon. He studied theology for two years at
Oxford University and wrote
The Council of Chalcedon and the Armenian Church, published in 1965 in London. Upon his return to Lebanon, he served as dean of the Antelias seminary. From 1963, he became an aide to Catholicos
Khoren I in which function he had many ecumenical contacts. He served as observer at the
Second Vatican Council, the
Lambeth Conference of 1968 and the
Addis Ababa Conference of the heads of the Oriental Orthodox Churches. He lectured on theology, literature, history and culture at universities in Beirut, Romania, Moscow and Kotayyam (India). His ecclesiastical career advanced quickly: in 1963 he was elevated to senior archimandrite and on January 19, 1964, he was consecrated
bishop by Catholicos Khoren. In 1971 he was elected Prelate of
the Diocese of
New Julfa in
Isfahan,
Iran. In 1973, he received the rank of
archbishop and was appointed Pontifical
Legate of the Eastern Prelacy of the Armenia's Holy Apostolic Church of America (in New York) and in 1975 its
Primate. During his time in the United States, he took special care of the younger generation of Armenians and played a key role in the fundraising for Lebanon in 19761977. ==Catholicos Coadjutor of the Holy See of Cilicia (1977–1983)==