Discusses the history of schisms and doctrinal deviations in Christianity from the founding of the Church to the 20th century. This book answers the question of who is a heretic and outlines the various heresies that arose from differences of opinion regarding the Christian message. The author argues that heresies arise from diversity of thought, personality, temperament, and ultimately from the reality of human freedom itself. The discussion begins with the early Church, touching on early Judaism, and continues through the great controversy that shook the Christian world.