This dissertation examines Billy Kim’s evangelism theology and methodology. Chapter 1introduces Billy Kim’s half-century evangelistic ministry in Korea and points out how his evangelism theology and methodology are related with the growth and stagnation of Korean Protestantism. Chapter 2 points out the historical context of Billy Kim’s childhood and his ministry in Korea. Chapter 3 illustrates his journey from a houseboy, to a pastor, evangelist, and CEO. Chapter 4 examines Billy Kim’s theology, which drove his evangelistic ministry. It pinpoints how evangelical theology influenced the formation of his theology. Chapter 5 examines the methodology of his evangelistic ministry. Billy Kim’s fervor for evangelism, along with the timely support of American Evangelicals, contributed to the rapid growth of Korean Protestantism. Yet, changes in Korean society brought challenges to Billy Kim’s evangelistic ministry and slowed the growth of Korean Protestantism. Chapter 6 provides a conclusion and recommendations for overcoming the stagnation of the growth of Korean Protestantism in the present day.