Muslim pilgrims read from a copy of the Koran as the pray on Mount Arafat, near the holy city of Mecca, ahead of the hajj main ritual, on October 14, 2013.
Using the CIA Factbook, we labeled the countries in the world where more than half the population considers themselves religiously affiliated. The darker shades represent the countries with the highest percentages of religious citizens. Click on any of the maps below to see an enlarged version.