Election and first deposition Isaac was elected catholicos after the death of his predecessor,
Aspuraces. He supported King
Khosrov IV of Armenia in his efforts to reunite the Armenian realm, which had been partitioned into Roman and Sasanian parts in 387. Khosrov was imprisoned by the Sasanian king in about 389, possibly because of his nomination of Sahak as catholicos without Persian approval. After Khosrov's imprisonment, Isaac was deposed as catholicos, but Khosrov's successor
Vramshapuh managed to have him restored to his position. Through Isaac's efforts the churches and monasteries destroyed by the Persians were rebuilt, education was cared for in a generous way, Zoroastrianism which
Shah Yazdegerd I tried to set up was cast out, and three councils held to re-establish ecclesiastical discipline. The catholicos was noted for his ascetic lifestyle.
Creation of the Armenian alphabet in front of the main building of
Yerevan State University Prior to the invention of the Armenian alphabet, the languages of the Armenian Church were Greek and Syriac. Armenia had been divided into Roman and Sasanian client kingdoms in 387. In the Roman part, however, the Armenians were forbidden the use of the Syriac language and used Greek instead, and the country gradually Hellenized; in the Persian part, on the other hand, Greek was absolutely prohibited, while Syriac was used. In this way the ancient culture of the Armenians was in danger of disappearing and national unity was seriously compromised. Isaac encouraged
Mesrop Mashtots to invent the
Armenian alphabet and himself translated and revised parts of the Bible. According to Ghazar Parpetsi, Mashtots and the first translators frequently turned to Isaac, who had received a solid education, for assistance while making the alphabet. Their translation from the Syriac
Peshitta was revised by means of the
Septuagint, and even, it seems, from the
Hebrew text (between 410 and 430). The liturgy also, hitherto Syrian, was translated into Armenian, drawing at the same time on the liturgy of Saint
Basil of Caesarea, so as to obtain for the new service a national color. Isaac had already established schools for higher education with the aid of disciples whom he had sent to study at
Edessa,
Melitene, Constantinople, and elsewhere. Through them he now had the principal masterpieces of Greek and Syrian Christian literature translated, e.g., the writings of
Athanasius of Alexandria,
Cyril of Jerusalem,
Basil,
Gregory of Nazianzus,
Gregory of Nyssa,
John Chrysostom,
Ephrem the Syrian, and others. The invention of the Armenian alphabet sped up the process of the Christianization of the Armenian population.
Second deposition and death In 428, the last Arsacid king of Armenia
Artashir was deposed by the Sasanian king with the help of most of the Armenian nobles. Isaac was against this and was himself removed from his position as Catholicos. An Armenian named Surmak was appointed in his place but was soon replaced by the Syrian bishop Brkisho. Isaac was imprisoned in Ctesiphon until 432, when he was allowed to return to Armenia and occupy certain offices within the church. Isaac refused to retake the patriarchate after the death of Catholicos Samuel, Brkisho's Syrian successor, in 437. Isaac died around 438 in the village of Blur in
Bagrevand. His body was taken to
Taron and buried in
Ashtishat. Since Isaac was the last male of the Gregorid line, his house's territories of Taron, Bagrevand and
Acilisene passed to the Mamikonians through Isaac's daughter Sahakanoysh, who was married to the Mamikonian prince Hamazasp. == Works ==