According to the CIA fact book, atheism doesn't even get it's category. To bolster its numbers, atheism has to be lumped in with agnostics, non-religious and secular just to reach 1.1billion. Even then there are twice as many Christians and 1.5 times as many Muslims. I was talking to a friend of mine at work who was asking me why I was arguing with atheists when they are such an insignificant minority?
http://en.wikipedia.org/wiki/List_of_religious_populations said:Religion Adherents
Christianity 2.1 billion
Islam 1.5 billion
Secular*/Nonreligious*/Agnostic/Atheist ≤ 1.1 billion
Hinduism 1 billion
Chinese traditional religion* 394 million
Buddhism* 376 million - 1.2 billion
Primal-Indigenous religions 300 million
African Traditional & Diasporic religions 100 million
Sikhism 28 million
Shinto 27-65 million
Juche* 19 million
Spiritism 15 million
Judaism 15 million
Baha'i 7 million
Jainism 5 million
Cao Dai 4 million
Zoroastrianism 2.6 million
Tenrikyo 2 million
Neo-Paganism 1 million
Unitarian Universalism 800,000
Rastafarianism 600,000