The Emperor Theodosios II began his reign in the year 408 at the age of seven, succeeding his father, Arkadios. He was called “the younger” in order to distinguish him from his grandfather Theodosios the Great. His sister Pulcheria instructed him in Christian piety, and so he had a great reverence for the Orthodox Faith. When Theodosios II assumed the throne, with the help of his sister Pulcheria. He was a strong supporter of the truth of the Orthodox Faith and defender of the Nicene Creed.
By an imperial decree of November 19, 430, the Third Ecumenical Synod met on June 22, 431 in Ephesus, which condemned the heretical beliefs of Nestorius. Because of the fervent piety and great service to Orthodoxy of Theodosius II, the Church has numbered him among its Saints.