Ferdinand Christian Baur 
Christianity and the Christian Church of the First Three Centuries [PDF ebook] 

Christianity and the Christian Church of the First Three Centuries is the first volume in Baur’s five-volume history of the Christian Church. It and the last volume, Church and Theology in the Nineteenth Century, are being published in new translations. This book, based on the second German edition of 1860, is the most influential and best known of Baur’s many groundbreaking publications in New Testament, early Christianity, church history, and historical theology. It is divided into six main parts and discusses such matters as the entrance of Christianity into world history, the teaching and person of Jesus, the tension between Jewish Christian and Gentile Christian (Pauline) interpretations and their resolution in the idea of the Catholic Church, the opposition of gnosticism and Montanism to Catholicism, the development of dogma or doctrine in the first three centuries, Christianity’s relation to the pagan world and the Roman state, and Christianity as a moral and religious principle.