The religiously unaffiliated are the third-largest group in the world, after Christians and Muslims, according to a new survey.
About one in six or 1.1-billion people profess to having no religious affiliation, according to a survey by the Pew Forum on Religious and Public Life released on Tuesday.
While the group includes atheists and agnostics, it is not exclusive to them.
"Surveys indicate that many of the unaffiliated hold some religious or spiritual beliefs [such as belief in God or a universal spirit] even though they do not identify with a particular faith," the forum said.
The Pew Forum conducted the study, called "The Global Religious Landscape", in 2010 and researched people in more than 230 countries and territories.
The survey found there were 2.2-billion Christians, about 32% of the world's population, and 1.6-billion Muslims.
The fourth-largest group in the world were Hindus, about one-billion, followed by about 500-million Buddhists.
More than 400-million, or 6%, of the world's population practice different folk or traditional religions, including African traditional religions.
The survey found about 14-million Jews, about 0.2% of the population. About 58-million people, less than 1% of the population, practice other religions including Bahá'i, Jainism, Sikhism, Shitoism, Taoism, Tenrikyo, Wiccanism and Zoroastrianism, amongst others. – Sapa