The number of Muslims grew from 11 million in 1900 to 234 million in 2010.
Christians have grown from 7 million in 1990 to the current 470 million. Fifty-seven percent of the population is Christian while 29 percent is Muslim.
Now this region between the Sahara Desert and the Cape of Good Hope is home to one-in-five of all of the Christians in the world.
The study was conducted by the Pew Forum on Religion and Public Life and involved 25,000 face-to-face interviews in 90 countries representing the sub-Sahara Africa.
The report notes that sub-Saharan African Christians and Muslims generally have a positive view of each other, and in most countries relatively few people think that there is hostility against Muslims or Christians.
While sub-Sahara Africa has almost twice as many Christians as Muslims, on the African continent as a whole the two faiths are roughly balanced, with 400 million to 500 million followers each.