Philip Jenkins on religion in Africa:

Over the course of the 20th century, millions of Africans transferred their allegiance from traditional primal faiths to one of the two great world religions, Christianity or Islam—but they demonstrated an overwhelming preference for the former. Around 40 percent of Africa’s population became Christian, compared to just 10 percent who chose Islam. As Muslims had earlier far outnumbered Christians, the result was to transform a massive Muslim majority into a reasonably equal confessional balance. Africa today is about 47 percent Christian, 45 percent Muslim, and some 8 percent followers of primal religions.