Religion in South Korea

Religion in South Korea is diverse. Most South Koreans have no religion. Buddhism and Christianity (Protestantism and Catholicism) are the dominant confessions among those who affiliate with a formal religion.^[3] Buddhism, which arrived in Korea in 372 AD, has thousands of temples built across the country.^[3]

According to a 2021 Gallup Korea poll, 50% identify with no religion, 17% with Buddhism, 16% with Protestantism, 6% with Catholicism, and 1% with other religions.^[4] In 2010, a Pew Research Center poll found that around 46% of people had no religion. This indicates a possible large increase in irreligion in the span of a decade.

Buddhism was influential in ancient times and Christianity had influenced large segments of the population in the 18th and 19th century, yet they grew rapidly in membership only by the mid-20th century, as part of the profound transformations that South Korean society went through in the past century.^[5] But they have shown some decline from the year 2000 onwards. Native shamanic religions (i.e. Sindo) remain popular and could represent a large part of the unaffiliated. Indeed, according to a 2012 survey, only 15% of the population declared themselves to be not religious in the sense of "atheism".^[6] According to the 2015 census, the proportion of the unaffiliated is higher among the youth, about 64.9% among the 20-years old.^[7]

Korea entered the 20th century with an already ingrained Christian presence and a vast majority of the population practicing native religion, Sindo. The latter never gained the high status of a national religious culture comparable to Chinese folk religion, Vietnamese folk religion and Japan's Shinto; this weakness of Korean Sindo was among the reasons that left a free hand to an early and thorough rooting of Christianity.^[8] The population also took part in Confucianising rites and held private ancestor worship.^[5] Organised religions and philosophies belonged to the ruling elites and the long patronage exerted by the Chinese empire led these elites to embrace a particularly strict Confucianism (i.e. Korean Confucianism). Korean Buddhism, despite an erstwhile rich tradition, at the dawn of the 20th century was virtually extinct as a religious institution, after 500 years of suppression under the Joseon kingdom.^[5][9] Christianity had antecedents in the Korean peninsula as early as the 18th century, when the philosophical school of Seohak supported the religion. With the fall of the Joseon in the last decades of the 19th century, Koreans largely embraced Christianity, since the monarchy itself and the intellectuals looked to Western models to modernise the country and endorsed the work of Catholic and Protestant missionaries.^[10] During Japanese colonisation in the first half of the 20th century, the identification of Christianity with Korean nationalism was further strengthened,^[11] as the Japanese tried to combine native Sindo with their State Shinto.

With the division of Korea into two states after 1945, the communist north and the capitalist south, the majority of the Korean Christian population that had been until then in the northern half of the peninsula,^[12] fled to South Korea.^[13] It has been estimated that Christians who migrated to the south were more than one million.^[14] Throughout the second half of the 20th century, the South Korean state enacted measures to further marginalise indigenous Sindo, at the same time strengthening Christianity and a revival of Buddhism.^[15] According to scholars, South Korean censuses do not count believers in indigenous Sindo and underestimate the number of adherents of Sindo sects.^[16] Otherwise, statistics compiled by the ARDA^[17] estimate that as of 2010, 14.7% of South Koreans practice ethnic religion, 14.2% adhere to new movements, and 10.9% practice Confucianism.^[18]

According to some observers, the sharp decline of some religions (Catholicism and Buddhism) recorded between the censuses of 2005 and 2015 is due to the change in survey methodology between the two censuses. While the 2005 census was an analysis of the entire population ("whole survey") through traditional data sheets compiled by every family, the 2015 census was largely conducted through the internet and was limited to a sample of about 20% of the South Korean population. It has been argued that the 2015 census penalised the rural population, which is more Buddhist and Catholic and less familiar with the internet, while advantaging the Protestant population, which is more urban and has easier access to the internet. Both the Buddhist and the Catholic communities criticised the 2015 census' results.^[7]