Frumentius
While teaching Ezana, Frumentius tried to convince as many people as he could to become Christian.  Once Ezana was an adult both Frumentius and his brother Edesius left Ethiopia. Edesius went back home to Tyre but Frumentius went to Egypt to convince  Athanasias the creator of the Athanasian Creed to appoint missionaries to Axum. So Athanasius appointed Frumentius as a bishop. Frumentius went back to Ethiopia this time with Christian priests to start Churches and to convince people there to become Christians. Frumentius even managed to get King Ezana to convert to Christianity. When the Roman Empire told Ezana to replace Frumentius with another bishop, because Frumentius didn’t believe in the Nicene Creed, Ezana said no.