oldest Christian denominations in Africa are the Eastern Orthodox Church of Alexandria, the Coptic Orthodox Church of Alexandria, and the Ethiopian Orthodox Tewahedo Church and Eritrean Orthodox Tewahedo Church (which rose to prominence in the fourth century AD after King Ezana the Great made Ethiopia one of the first Christian nations.) In the first few centuries of Christianity, Africa produced many figures who had a major influence outside the continent, including St Augustine of Hippo, St Maurice, Origen, Tertullian, and three Roman Catholic popes (Victor I, Miltiades and Gelasius I), as well as the Biblical characters Simon of Cyrene and the Ethiopian eunuch baptised by Philip the Evangelist. Christianity existed in Ethiopia before the rule of King Ezana the Great of the Kingdom of Axum, but the religion grasped a strong foothold when it was declared a state religion in 330 AD, becoming one of the first Christian nations. The earliest and best known reference to the introduction of Christianity to Africa is mentioned in the Christian Bible's Acts of the Apostles, and pertains to the evangelist Phillip's conversion of an Ethiopian traveller in the 1st century AD. Although the Bible refers to them as Ethiopians, scholars have argued that Ethiopia was a common term encompassing the area South-Southeast of Egypt. Other traditions have the convert as a Jew who was a steward in the Queen's court. All accounts do agree on the fact that the traveller was a member of the royal court who successfully succeeded in converting the Queen, which in turn caused a church to be built. Tyrannius Rufinus, a noted church historian, also recorded a personal account as do other church historians such as Socrates and Sozemius. Some experts predict the shift of Christianity's center from the European industrialized nations to Africa and Asia in modern times. Yale University historian Lamin Sanneh stated, that "African Christianity was not just an exotic, curious phenomenon in an obscure part of the world, but that African Christianity might be the shape of things to come." The statistics from the World Christian Encyclopedia (David Barrett) illustrate the emerging trend of dramatic Christian growth on the continent and supposes, that in 2025 there will be 633 million Christians in Africa. A 2015 study estimates 2,161,000 Christian believers from a Muslim background in Africa, most of them belonging to some form of Protestantism. Islam Islam is the other major religion in Africa