Using information from last year’s global survey of religiosity (conducted by WIN-Gallup International), the Washington Post put together a nifty map explaining where the world’s “convinced atheists” lived:
China is far and away the “winner,” though the country’s Communist history and hostility to religion has a lot to do with that:
The official ideology of the Communist government scorned both “new” Western religions and more traditionally Chinese faiths, destroying countless temples and relics during the Cultural Revolution of 1967 to 1977. While today’s Chinese leaders do not seem to share Mao Zedong’s fervent belief that China’s rich religious history was holding it back from modernity, nor do they seem prepared to bring that history back.
Saudi Arabia is also a little darker than you might expect, which is a surprising thing to see.
Keep in mind that this global survey is really a compilation of a variety of surveys, each of which may have its own flaws. Also, we don’t know how many people answered that they were religious just to save face and stay out of the crossfire.