This paper argues that Anabaptism, realted to Post-Constantinianism, protested thoroughly and radically against the Christendom and its ideology, Constantinianism, which was a system that forced the Christian faith through the solidarity and the alliance with the power of the state. Three things are needed to explain that Anabaptism is Post-Constantianism: the rejection of infant baptism which was the origin of the Anabaptist. the martyrdom of Michael Sattler, the author of the Schleitheim Confession of the Anabaptists, and religious freedom that made them tolerating differences in faith and advocated religious tolerance. Even if it were paganism and heresy, they, who strongly opposed the solution of force and power, went too far ahead of their times. On the verge collapse of Constantine system and its world view, re-examining the Anabaptists, who were the most radical critic among the Reformers, will be the way to re-member and re-present the Reformation and be the alternative for Korea churches.