In about 356, the Emperor Constantius II wrote to King Ezana and his brother Saizanas, requesting them to replace Frumentius as bishop with Theophilus, who supported the Arian position, as did the emperor.
Orthodox Christianity became the established church of the Axumite Kingdom under king Ezana in the 4th century through the efforts of a Syrian Greek named Frumentius, known to the churches' followers as Abba Selama, Kesaté Birhan ("Father of Peace, Revealer of Light").