The History of the Christian Church until the Great Schism of 1054 is a sincere and unbiased history of the Church, written by the Russian historian and theologian Mikhail Posnov. Posnov through this study of Church history discovered the importance of the teaching authority of the Bishop of Rome. The book has been called a most valuable tool for students of Christian Church history. The most important characteristic of the text is its original and profound use of primary historical sources. The book is neither polemical nor triumphalistic but scholarly in its pursuit of truth concerning the period of the undivided Church. It should be an impetus to reconciliation and understanding for Catholic and Orthodox Christians and a source of great insight into the early Church for Protestant Christians.