Cheondoism

Cheondo (Korean: 天道; 천도; Way of Heaven) is a syncretic religion originating in the Kingdom of Korea around the 11th century. Cheondo originated as a "compromise" at a time when Christianity and Buddhism were clashing in the Khanate, with the former quickly replacing the later. Cheondo was formulated primarily from the writings of 9th Century Buddhist apologist Chung Baek-Hyeon, who drew similarities between Christian and Buddhist ideas, and drew common ground between the two faiths. This went to its extreme with the teachings of Eun Yose-O, a convert to Buddhism from Christianity, who later became nostalgic for the faith he grew up with, but was still a firm believer in the religion he had converted to. Eun began to write essays attempting to fuse Christianity with Buddhism and wrote extensively on his ideas for how such a fusion could be tenable. Eun's works would become influential in the movement that would become Cheondo.

Cheondo had a modest growth, though there was much criticism of the movement from both of its parent religions. Cheondo largely existed as an alternative to those who had disagreements with the mainstream Nestorian Church that dominated Korea. When the ideas of Protestantism reached Korea in the mid 17th century, Cheondo had a marked decline, with many jumping from it to the newly formed Protestant sects. Following the Wars of Reformation, when the Naimans outlawed Protestantism and gave all Protestants the option to either return to Nestorianism, Convert to another religion, or be executed, some opted to convert to Cheondo, though it later became apparent that many groups were fronting as Cheondo organizations to hide their Protestantism under the radar.

Cheondo has been in constant decline since the 17th century, with only about 0.8% of Koreans identifying with the religion.