Roman Church. There is only one See founded on Peter by the word of the Lord... Outside of the Church, no one can hope for life or salvation unless he is excused through ignorance beyond his control." It is also a common theme in Catholic devotional and catechetical literature: "The Holy Catholic and Apostolic Church is the only flock of which Jesus Christ, the Son of God, is the only Shepherd." (Catholic Book of Prayers, Pg. 236, "One Flock, One Shepherd") A 2007 declaration of the Congregation for the Doctrine of the Faith clarified that, in this passage, "'subsistence' means this perduring, historical continuity and the permanence of all the elements instituted by Christ in the Catholic Church, in which the Church of Christ is concretely found on this earth", and acknowledged that grace can be operative within religious communities separated from the Catholic Church due to some "elements of sanctification and truth" within them, but also added "Nevertheless, the word 'subsists' can only be attributed to the Catholic Church alone precisely because it refers to the mark of unity that we profess in the symbols of the faith (I believe... in the 'one' Church); and this 'one' Church subsists in the Catholic Church." The Catholic Church teaches that only corporate bodies of Christians led by bishops with valid holy orders can be recognized as "churches" in the proper sense. In Catholic documents, communities without such bishops are formally called ecclesial communities. Eastern Orthodox tradition The Eastern Orthodox Church each claims to be the original Christian Church. The Eastern Orthodox Church bases its claim primarily on its assertion that it holds to traditions and beliefs of the original Christian Church. It also claims that four out of the five sees of the Pentarchy (excluding Rome) are still a part of it. Oriental Orthodox tradition The Oriental Orthodox Churches claims to be the original Christian Church. The Oriental Orthodox churches' bases their claim primarily on its assertion that it holds to traditions and beliefs of the original Christian Church. They never adopted the theory of the Nature of God, which was formulated later than the break that followed the Council of Chalcedon. Lutheran tradition The Lutheran churches traditionally hold that their tradition represents the true visible Church. The Augsburg Confession found within the Book of Concord, a compendium of belief of the Lutheran Churches, teaches that "the faith as confessed by