Religious organizations, especially Christian churches, played key roles in the democratization of South Korea. Prominent transition scholars have paid attention to the contribution of Christian churches, both Protestant and Catholic, to the Korean democratic transition. Korean Christian churches not only were involved in democratization to seek legitimacy in the eyes of their constituencies, but also they accepted the invitation from social movements to join the struggle for democratization. The pursuit of new spiritual and nonspiritual formulas for legitimacy to satisfy domestic and foreign constituencies motivated churches to participate in democratization. Democratic engagement was the strategic choice of church leaders to maximize their market shares. To recruit new Christians in the wake of rapid social changes, such as industrialization, urbanization, and the expansion of higher education, Christian leaders adopted the strategy of participating in and leading the struggle for democracy. During the nationwide mobilization for democracy, church and student networks were the most effective in organizing opposition to the government.