The purpose of this study is to introduce and evaluate Rodney Stark’s Theories of Rational Choice in Religion. To this end, chapter I identifies some foundational issues related to the historiography of the writing of church history after Ranke, including the work of Max Weber, Ernst Troeltsch, and H. Richard Niebuhr. Chapter II describes the formation of the sociology of religion and surveys Stark’s attempt to combine sociology and church history. Stark emphasizes a sociological approach to church history over traditional approaches involving psychology or doctrinal interpretation. His approach uses sociological elements such as demography, in addition to social, political, and cultural interpretative models. Chapter III delineates Stark’s position with regard to Theories of Rational Choice in Religion. He first defines these theories by arguing that they suggest “people are as rational in making religious choices as in making secular decisions.” He further qualifies this, claiming that “within the limits of their information and understandings, restricted by available options, guided by their preferences and tastes, humans attempt to make rational choice.” In short, people usually attempt to pursue what they perceive to be the best option for achieving their goals in religion. The major content of such Rational Choice theories is that subjects adopt a cost-benefit assessment before adopting a new religious product such as a church or a denomination. These theories do not apply in the case of state churches but to free churches in the context of a religious economy. He defines this economy as “consist[ing] of all the religious activity going on in a society; a ‘market’ of current and potential adherents, a set of one or more organizations seeking to attract or maintain adherents, and the religious culture offered by the organization(s).” Thus, Stark proposes that religion is necessarily pluralistic in such a religious market. Chapter VI of the present study concludes with an emphasis on the a critical evaluation of Stark’s theory and the possibility of applying these doctrines to Korean churches. This paper also emphasizes the urgent necessity of dealing with new sects or churches in Korea.