The Episcopal Book Of Common Prayer, the BCP, more than any other document except the Holy Bible, defines the beliefs of the Episcopal Church,which is the only province of the Anglican Communion in the United States of America recognized by the Archbishop of Canterbury.

Unlike other Christian Bodies, what Anglicans believe is not defined in a "confession of faith." The only credal statements required of Anglicans are the Nicene Creed, which contains the totality of Christian belief, and the Apostles' Creed, which is the statement of belief made by those when they are baptized Christians in the Episcopal Church. Both credal statements are contained in the BCP, which is the foundational document for belief and worship in the Episcopal Church. 

The Book of Common Prayer has its roots in the first Book of Common Prayer adopted in the Church of England in 1549, which prescribed the first liturgy adopted for worship in the English language and was the only liturgy authorized for worship in the Church of England when the English Church made its final rejection of the authority of the Bishop of Rome after the death of Mary Tudor, who had restored the Church of England to the Roman Catholic Church when Henry VIII died.

During the reign of Elizabeth I, the BCP was important as a unifying religious document, but it was also the primary means by which Elizabeth accomplished political unity in England as well. When Elizabeth ascended to the throne, she inherited a kingdom deeply divided between the adherents of the "old" religion that recognized the authority of the Roman Catholic pontif, and advocates for Reformation.  Had Elizabeth chosen either of these options, England would have been engulfed in a bitter civil war. Instead she chose neither and established the Church of England under her own authority, the means by which her father Henry VIII, had rejected the authority of Rome. She imposed no specific religious beliefs on her subjects, but rather required that they worship in "common prayer" using the liturgy of the BCP.  Their personal beliefs were left up to their individual consciences. At the end of her long reign, the BCP had become accepted by all but the most radical "catholics" and "protestants" as an adequate statement of what they believed.

Those Anglicans who understand the Anglican Communion and know the history of the BCP, recognize that it is in "common prayer" that we maintain the unity of the Body of Christ while allowing for a broad range of diversitiy in belief.  Those "Anglicans" who seek to impose their own interpretation of the Christian religion  on other Anglicans both misunderstand what it is to be "Anglican" and in doing so essentially repudiate its genious.

The BCP has been revised numerous times since 1549 in order to reflect changes in the English language and to serve the needs of various Anglican provinces thoughout the world , including translation into many indigenous tongues. Although the BCP has been revised, however, it has retained its essential character and the majesty of its language. Over its history, it has had a profound influence on the English language and its literature.