When a believer acknowledges the presence and power of God within her, not only is her job performance blessed, but the performances of her co-workers is also blessed beyond measure. Another great power came in the person of the Imam of Harar in Ethiopia, Ahmad ibn Ibrahim al-Ghazi, also known as Ahmad Gurey or Gragn. Uthman had been driven out of Hejaz and found shelter at Axum in the Tigray Region of Ethiopia under the protection of the Axumite king, Aṣḥama ibn Abjar. Those who refused to embrace the new religion were compelled to seek refuge in the mountains of southern Ethiopia. A majority of the Tigrinya who constitute almost 60% of the population are Christian. According to a 2018 report from the United States Department of State, the population in southern and central Eritrea is primarily Christian, while the population of northern Eritrea is primarily Muslim. In the 2010 Eritrea Population and Health Survey, conducted by the Eritrean National Statistics Office and the Fafo Institute for Applied International Studies, 61.4% of all survey respondents reported being Christian (56.3% Orthodox, 4.2% Catholic, and 0.8% Protestant), with 38.4% reporting being Muslim, and the remaining 0.2% adhering to traditional faiths. The majority of the Kunama are Catholic, with a small minority of Muslims and some who practice traditional indigenous religions.

Non-response bias arises when the characteristics of those who participate in a survey are different from those who do not. About 5% of the Tigrinya are also Muslims; they are known as the Jeberti, though they claim a different ethnic background from the Biher-Tigrinya; the Rashaida are an Arab tribe who migrated from the Hejaz region of Saudi Arabia in the 19th century. The Lutheran Church of Eritrea and its Swedish and Eritrean missionaries were the ones who translated the Bible from Ge’ez language only understood by higher clergymen, into the Tigrinya language and other local languages and their main goal was to reach and “enlighten” as many people as possible in the world through education. The various estimates shown above place Christianity (all denominations) as the religion of between 47% and 63% of the population of Eritrea. Pew based its estimate of Eritrea’s religious composition on the 2002 survey referenced above.

In a 2016 report by Aid to the Church in Need, that organization estimated around 50 percent of Eritrea’s population adhered to Islam, and 48 percent followed Christianity, with all remaining religions accounting for two percent. In 2015, Pew Research estimated that, by 2020, 62.9% of the population would be Christian, while 36.6% would be Muslim, with the rest following other religions. The 2011 edition of the Encyclopedia of Global Religion matches the Pew Research Center estimate of 63% Christian, breaking it down further to: 58% Orthodox; 5% Roman Catholic; and less than 1% Protestant. Catholics in Eritrea mainly follow the Ge’ez variant of the Alexandrian Rite, but the Roman Rite is also used. When Eritrea was an Italian colony, all the colonists and the Italian military were of the Latin Church: in 1940 they constituted 11% of the total population. Today the church is a distinctly Eritrean church, using the Ge’ez language in the liturgy, although Masses continue to be celebrated also in Italian and Latin for the small Italian and Italo-Eritrean community, mainly in Asmara.

A large majority of the Christian population of Eritrea belongs to the Eritrean Orthodox Tewahedo Church, which used to belong to the Ethiopian Orthodox Tewahedo Church. The Aksumites erected a number of large stelae, which served a religious purpose in pre-Christian times. However, the number of adherents is subject to debate. However, there was tension between the Catholic Church as the Roman Catholic Italians resisted and discouraged the spread of Protestantism in their colony and even lay prohibitions and numerous constraints on the activities of the Swedish missionaries. By the 9th century, Islam had spread to the eastern coasts of Eritrea and some indigenous groups in the region began adopting the religion. Islam later spread in Eritrea under the Ottoman Empire when ethnic groups like the Tigre people in mainland Eritrea began converting to Islam. The history of Islam in Eritrea can be traced back to the beginnings of the religion in the 7th century.