Statistical data on religious affiliation, like those on ethnic groups, are unreliable. Most Orthodox Christians are Amhara and Tigray, two groups that together constitute more than 40 percent of the population. When members of these two groups are combined with others who have accepted Orthodoxy, the total Christian population might come to roughly 50 percent of all Ethiopians.

Muslims have been estimated to constitute 40 percent of the population. The largest ethnic group associated with Islam is the Somali. Several other much smaller Islamic groups include the Afar, Argobba, Hareri, Saho, and most Tigrespeaking groups in northern Eritrea (see Ethiopia's Peoples, this ch.). Oromo also constitute a large proportion of the total Muslim population. There are also Muslims in other important ethnic categories, e.g., the Sidamo speakers and the Gurage. In the far north and the east, and to some extent in the south, Islamic peoples surround Orthodox Christians.

The only people (variously estimated at 5 to 15 percent of the population) who have had little if any contact with Orthodox Christianity or Islam live in the far south and the west. Included among adherents of indigenous religions are most of those speaking Nilo-Saharan languages and many of those speaking Omotic and Cushitic, including sections of the Oromo, such as the pastoral Borana. It is among these peoples that the few converts to missionary Christianity-- Protestant and Roman Catholic--are to be found.

Data as of 1991