Historical research on the spread of Christianity in colonial Northern Nigeria has been hampered by a focus on the wrong issues. The population of the colony was predominantly Muslim, but the colonial territory created by the British contained large populations of African traditionalist peoples. During the colonial era the British government prohibited Christian proselytization of Muslims. Historical research had focused on the battle between colonial administrators and missionaries over entry into Muslim areas, a battle missionaries lost. But during the colonial era Christian missions experienced real success in Christianizing traditionalist peoples. The colonial government also sought to impede this development, significantly by using the same rules that prohibited the proselytization of Muslims to prohibit the proselytization of traditionalists. This article makes the case that the government’s efforts to halt the spread of Christianity to traditionalists, not Muslims, should become the focus of new research.