"This extraordinary well-written and exciting book is a thorough and systematic exploration of the spread of early Mesopotamian Christianity and its disputed theology undertaken by a leader of the Church of the East. It is an important historical and patristic study for the self-understanding of the Assyrian Church today. Mar Bawai Soro's scholarship is tightly reasoned and marked by the utmost clarity. Being truthful to the tradition of his Church, the research of Mar Bawai significantly contributes not only to ecumenical encounter but also leads to a better mutual understanding of Fathers, Councils, and Theologies within their respective historical and cultural contexts." (Prof. Dietmar W. Winkler, Chair of the Department of Biblical Studies and Ecclesiastical History, University of Salzburg)