Son of Saint Nerses the Great, Catholicos of Armenia. Studied at Constantinople. Married layman for several years. Widower. Monk. Catholicos of Armenia in 390, succeeding his father to the office. He secured recognition from Constantinople of the status, rights and independence of the Armenian Church. From his position he worked to reform the Armenian Church, evangelize the Armenian people, and establish an Armenian identity. He enforced Byzantine canon law, insisted on celibacy for bishops, built churches, schools and monasteries, and fought Persian paganism. Isaac worked with Saint Mesrop the Teacher to evangelize Armenia, and to develop and alphabet of the Armenian language. He supported the translation the Bible and the Greek and Syrian Doctors of the Church into Armenian Isaac served as both civil and religious ruler of his people, established a national liturgy, and was responsible for the beginnings of Armenian literature. He was driven into retirement in 428 when the Persians conquered part of his territory, but later returned as Catholicos at Ashtishat from where he worked until he death. Considered the founder of the Armenian Church.
- 440 at Ashtishat of natural causes
- “Saint Isaac the Great“. CatholicSaints.Info. 5 September 2013. Web. 27 November 2015. <>