“The pious Emperor Justinian was a fervent Christian and a man of genius in every field. His long reign (527-65) was a decisive period in the history of the Empire from the administrative, diplomatic, military, economic, legal, cultural and ecclesiastical points of view. He was the real founder of the Christian Empire, who brought together again the old Roman Empire that had been torn to pieces by barbarian invaders. He believed that upholding the Orthodox faith and maintaining the symphony of Church and State were essential for the well-being of the Empire. He had a deep knowledge of theology and wrote several treatises on dogmas of the faith. He forbad pagan worship in the Empire, and was unremitting in pursuit of heretics and sectarians. He did all he could to reconcile the Monophysites to the Council of Chalcedon. In 553, he summoned to Constantinople the fifth Ecumentical Council (25 July), which reaffirmed the condemnation of Nestorius and also condemned Origen.
“The splendor of the churches and of everything that testified to the divine glory was brought to a culmination in the Empire of Justinian. He rebuilt the Great Church of Saint Sophia in Constantinople where, it was said, the service of God was so wonderfully ordered that it was as if heaven had come down to earth. He made great gifts to the monasteries of Egypt and of Palestine and built the Monastery of Saint Catherine at Mount Sinai. In all that he did, he had the help and support of his wife, the pious Empress Theodora. Justinian died on 14 November 565, without having been able to restore full unity to the Church, but he had set the Empire on firm foundations that would endure for centuries.” (Synaxarion)
It was Justinian who built the great Church of the Holy Wisdom (Agia Sophia), perhaps the most magnificent Christian church. The hymn “Only-begotten Son” was inserted in the Divine Liturgy at his command, and is thought to have been composed by him.
Note: There is some controversy about the inclusion of Justinian in the Synaxaria. His fervent labors to reconcile the Monophysites to the Church have led some writers to conclude that he himself embraced Monophysite errors; others dispute this. Lacking the wisdom to resolve the question, we only note that he is included in Ormylia Monastery’s Synaxarion (quoted above), but some Synaxaria have turned his commemoration into that of the Emperor Justin (518-527).