Book excerpt: The Orthodox Church is one of the three major branches of Christianity. There are over 300 million adherents throughout the world. The Orthodox Church is a fellowship of independent churches, which split form the Roman Church over the question of papal supremacy in 1054. The Orthodox adherents include people in: Greece, Georgia, Russia, and Serbia. There are an estimated one million members in the United States. This Advanced book explains the basic principles of Orthodox Christianity and describes in detail the holidays observed by the Orthodox Church. In addition, relevant book literature is presented in bibliographic form with easy access provided by title, subject and author indexes.