The Book of Concord is the historic doctrinal statement of the Lutheran Church, consisting of ten credal documents recognized as authoritative in Lutheranism since the <answer>16th</answer> century. However, the Book of Concord is a confessional document (stating orthodox belief) rather than a book of ecclesiastical rules or discipline, like canon law. Each Lutheran national church establishes its own system of church order and discipline, though these are referred to as "canons."
Beginning in what century was the Book of Concord a central part of the Lutheran Church?
16th