Kenya is overwhelmingly Christian, around 80 to 85 percent per most estimates including Pew Research's Religious Composition of the World, 2010-2020, split between Protestant and Catholic communities of roughly comparable size, with a Muslim minority of around 10 to 11 percent concentrated along the coast and in the northeast, and small indigenous traditional religion adherents among various ethnic groups.
Coastal Kenya's Islam arrived via Indian Ocean trade with Arabia and Persia from as early as the eighth century, producing the Swahili civilization, a Bantu-Arab-Persian trading culture centered on city-states including Mombasa, Lamu and Malindi that fused African, Islamic and Indian Ocean influences into a distinct coastal identity and the Swahili language itself, which carries substantial Arabic vocabulary. Christianity arrived substantially through nineteenth-century missionary activity under British colonial rule, and independent Kenya's founding president Jomo Kenyatta, raised Christian though of Kikuyu ethnic background, navigated a religious landscape that blended mission Christianity with strong indigenous religious currents, including the Mau Mau independence movement's partial use of traditional Kikuyu oathing rituals alongside its anticolonial politics in the 1950s.