According to the results of the census of 2015, more than half of the South Korean population (56.1%) declared themselves not affiliated with any religious organizations. In a 2012 survey, 52% declared themselves "religious", 31% said they were "not religious" and 15% identified themselves as "convinced atheists". Of the people who are affiliated with a religious organization, most are Christians and Buddhists. According to the 2015 census, 27.6% of the population were Christians (19.7% identified themselves as Protestants, 7.9% as Roman Catholics) and 15.5% were Buddhists. Other religions include Islam (130,000 Muslims, mostly migrant workers from Pakistan and Bangladesh but including some 35,000 Korean Muslims), the homegrown sect of Won Buddhism, and a variety of indigenous religions, including Cheondoism (a Confucianizing religion), Jeungsanism, Daejongism, Daesun Jinrihoe, and others. Freedom of religion is guaranteed by the constitution, and there is no state religion. Overall, between the 2005 and 2015 censuses, there has been a slight decline of Christianity (down from 29% to 27.6%), a sharp decline of Buddhism (down from 22.8% to 15.5%), and a rise of the unaffiliated population (from 47.2% to 56.9%).