The constitution of the Republic of Korea clearly states the separation of church and state. While pure religious action should be separated from politics, Koreans with religion have some duties and rights based on the fact that religious people also are members of the Korean nation and society. This article aims to describe an aspect of the relationship between politics and religions with a special attention to Christianity. First of all, Christianity of Catholic and Protestant played a great role in the building of the Republic of Korea. After the World War Ⅱ, other religions in Korea did not support liberal democracy. Also they had a very ambiguous attitude toward democracy. Some of them accepted even communism. In the ideological chaos, Christianity clearly counted as one of the important anticommunistic groups. At this point, Christianity should be considered as one of great contributors to the nation buildings of the South Korea. This close relationship of Christianity and anticommunism has been maintained from the World War Ⅱ to the present day. However, several presidents of Korea became dictators in the name of anticommunism so that many liberal Christians have protested against authoritarian government as well as anticommunism which became a hated word in Korean liberal society. Many struggles between governments and liberal Christians had been appeared in other areas such as industrial problems, rural society, as well as environment. Recently, many Buddhists has been strongly involved in such agendas of liberal Christianity. During transition from industrialization to democratization in South Korea, this nation has tried to find out a national identity and the Korean government have supported traditional religions such as Buddhism under the title of support of traditional and national culture. This support from government has been appeared in the area of culture, tourism and education. At this point, traditional and national religions of the South Korea have received a lot of financial aid from government.