We tend to think of orthodox Christians as oddly dressed and mysterious Russians and Greeks who practice their religious beliefs in the churches as they were before the rise to power and evolution of the Catholic church; and of Catholics as the orthodoxy that existed before the rise to power and evolution of the protestant churches.
The truth about orthodoxy lies in how observant the individual is, and what dogma, mythology, ritual, study, and fellowship the indivual follows. In other words, as churches evolved after the apostles Peter and Paul went on to spread the word, what was left behind and what remains as a part of a person's religious practice?
There is an amazing amount of orthodoxy in the mainstream and established churches. But there is also a lot of adaptation to accomodate different cultural, ethnic, and social norms, history, mythology, culture and values. Many falsely believe that the African slaves that were forced to come to America lost their African culture. That is definitely not true, the music, rhythms and culture of Africa were simply remembered in secret and incorporated into the way that African Americans celebrate their religion. In fact, the early African American churches provided excellent ways to conduct the underground railroad, to pass messages and intelligence during the Civil War, and to teach individuals to read and write. As a result, the predominantly African American churches also serve as centers of community issues and political activism, as do other christian churches that serve ethnic communities.
Common to most Christian churches and religions is the acceptance of Jesus Christ, belief in the miracles that Jesus enacted, and belief that he rose and walked the world after his death.
Study of the the bible, which in it's many forms, is close to the original King James version. The King James version is based on translations from the Hebrew and the Greek of the Old and New Testaments and the Aprocrypha, the "Bishops Bible" and the "Geneva Bible". Ironically, King James never approved or ordered the bible that bears his name to be the official bible of his kingdom.
The rituals of baptism, holy communion, marriage, funerial rites, group or individual prayer, and observance of a special day that is dedicated to resting and observance are highly similar in the protestant religions, but when protestants experience a Shabbat, Passover Seder, and Catholic mass, they are shocked to find that there are many similarities in ritual and in the dogma behind the rituals.
Another similarity of orthodoxy is in the required education for leading the mainstream of Christian churches. Just as priests studied extensively, most Christian churches are led by highly educated pastors and ministers who have completed some form of seminary educations, although there are some charismatic leaders who have relatively little formal education.
Born in the adherence to the teachings and direction of the apostles, and evolved from the Catholic church and orthodox churches, the Christian religion has many forms and many new orthodoxies, some of which have taken deviant paths into cult and radical organizations, but most of which are incredibly loyal to the written word as the source of law, historical understanding, and guidance in life.
The Truth All About, "The King James Bible"