Abstract Christian has endured many great changes during the last 2000 years, but as an independent voice, Christian affects the world continuously. The vitality Christian has is mostly due to the endeavor of hundreds of theologians. Reinhold Niebuhr is the kind of scholars. Niebuhr’s attribution to Christian is his Christian Realism ethics, which showed the relevance to social situation in the early half of 20 century. Among the critics of him, Frankena is a unnoticeable figure through which we can know the points of Niebuhr’s view on the relation of Christian ethics and the modern society.