This ambitious infographic from design agency Accurat (which previously made this map of Nobel Prize winners, and this one of apocalypse false-starts) crunched the numbers on religion worldwide, creating a map showing population, religion, and changes in religion for 1960 and 2010--for every country.
It's a little complicated to read--there's a ton of data here, after all--but each number and corresponding shape represents a different country. The shapes are split up by colors representing different religions; if a country has a "dominant" religion, meaning more than 50 percent identifies with the same group, then the shape takes a single color. Otherwise, it's split into multiple colors. The bigger the shape is, the larger its population. On the left are countries' religions and populations in 1960, and on the right, in 2010.