There is virtually no nation on earth that is without some community of Christian believers.

An acceptance of Jesus as  Messiah, the Son of God, is central to the faith, and is Christianity's "basic doctrine".

Many divergent traditions and structures that have emerged over the centuries as the result of disagreements over doctrine and practice; in part,  because the role and teachings of Jesus himself remain, after two millennia, a fundamental mystery.

At first, the Church was in disagreement between the Roman/Latin and Greek members.  This conflict created the Greek Orthodox or Eastern Orthodox Church and the Western or Catholic Church. 

The Eastern Orthodox Church concentrated in the Middle East and Russia and is now often refered to as the Ukranian Church. 

The Catholic Church grew and spread much more rapidly through Europe  and became a large world power.  There came calls for change as a result of some abuses of this power, and there became the Protestant Reformation

Other Facts:

Easter is the most important Christian holiday.

As of this writing, Easter (or Pascha) is celebrated according to one calendar tradition among believers in the West, and another among Orthodox believers.

Along with Easter, other important Christian observances include Christmas, Epiphany, Ash Wednesday, Good Friday, Pentecost, and the Feast of the Assumption.

In addition to the major holidays discussed here, Christianity is enriched by many variant traditions within the manifold expressions of the faith.

The Types of Christianity

Catholicism

Roman Catholics believe that Jesus was the son of God. 

There are sacraments: baptism, confirmation, the Eucharist (shring the body and blood of Christ during Holy Communion), penance/confession, the anointing of the sick, marriage, and holy orders for those living the clergy life. 

The Church is of divine revelation. The Pope is the spiritual authority and the bishops  of the Church have been assigned earthly domination over the spiritual matters of the church.  

The Human Soul is immortal. God is objective and exists in trinity: The Father, The Son, and the Holy Ghost. 

The Virgin Mary, mother of Jesus, is the mother and saviour of all humankind who is above sin. 

The Orthodox Church

The differences between the Catholic and Orthodox churches are more in the way they practice than in what they practice.  For example, Orthodox churches use leavened (yeast) bread in communion, while the Catholic church uses unleavened bread (like matzoah or cracker) for communion. Orthodox priests may marry before they are ordained.  The Orthodox church operates much more independently between parishes than the Catholic church does, and there is not as much emphasis on the hierarchy of clergy. 

Protestantism

From a single point of origin, the European religious revolutions, the religions designated as "Protestant" form the most diverse strand of the three great divisions within Christianity. The variety can be more than a little intimidating, because the collection of Protestant views presents a rich profusion of Bible-based traditions. The authors respect and honor the validity and devotion of the many Protestant traditions, not all of which can be identified here.

"Protestantism" is an umbrella term for a set of traditions that came into existence after the Reformations. If there is a single common thread among the traditions in this group, It is probably rooted in ideas of group autonomy and respect for individual experience. It has been said, for example, that Catholics come to Christ through the church, while Protestants come to the church through Christ.

This is not to say that most early Protestants believed in religious toleration and pluralism. (In the 16th and 17th centuries, such ideas were reserved for the radical fringe.)

Pentecostalism is a global movement emphasizing an ecstatic experience of God, often resulting in glossolalia (speaking in tongues). Major Pentecostalist denominations include the Church of God in Christ and the Assemblies of God.

Different Drummers: "Distinctive" Protestant Movements

The Quakers (or Friends) reject the necessity of ordained ministers and external sacra-ments, viewing all aspects of life itself as sacred. This pacifist tradition holds that every believer is gifted with "inner light." Friends gather in weekly Meetings to pray silently together and to share revelation as the Spirit dictates.

Extraordinary piety and a commitment to live as simply as possible mark the practices of active Mennonites, who refuse, on religious grounds, to hold public office or serve in any military capacity. The Mennonite tradition traces its roots to the radical fringe of the early Reformation, the Anabaptists. Another such group are the Amish, who reject many modern technological advances and severely limit contact with the outside world.

The Unitarian Universalist Association, which includes both Christian and non-Christian members, is among the most open and tolerant of Protestant religious traditions. Unitarian Universalists reject the doctrine of the Trinity, seeing Christ as a great teacher, not a divine incarnation. They tend to avoid dogma as restrictive and even presumptuous, choosing to emphasize inclusiveness and understanding rather than a specific religious creed.

The Christian Science movement, founded by Mary Baker Eddy, holds that the spiritual world is the true reality, compared to which the material world is an illusion. Christian Scientists believe that sin and illness can be overcome by spiritual powers. For this reason they tend to avoid medicines and medical procedures in favor of divine healing.

Seventh-Day Adventists celebrate the Sabbath on Saturday (rather than Sunday) and anticipate the imminent Second Coming of Christ.

Jehovah's Witnesses accept the Bible as factually true in every detail and anticipate the coming of God's kingdom after the battle of Armageddon, which is considered imminent and which is expected to be followed by a thousand-year reign of Christ on earth.

The guiding accents in the Protestant experience have been the formation of communities and the power of direct experience. Protestants claim "the priesthood of all believers by which they assert that lay believers have the same access to God as clergy-that all have a religious vocation, whether farmers, factory workers, parents, or ministers.

Two other fundamental doctrinal points set Protestant Christians apart from believers in the Roman Catholic tradition. The Bible is regarded as the only source of infallible, received truth, and the believer is justified by God's grace, obtained through his or her faith in Christ not by good deeds or the mediation of any religious institution.

In practice, the vast majority of Protestant denomination -have also rejected the notion of clerical celibacy. A few, including the shakers; advocated celibacy among all believers, relying on the recruitment of outsiders to perpetuate the faith.

An interesting Christian sect, the Mormons.  Download the entire Book of Mormon, courtesy of Project Guttenburg, here.

Faith, Not Works

Martin Luther, the first and one of the foremost Protestant reformers, interpreted certain passages of the New Testa-ment to mean that God's grace alone, and not the good works of individuals, served as source of salvation through faith. Luther's doctrine won an immediate following among academics, clergy, and laity.

John Calvin was another reformer of significant influence. An exiled French theologian of the generation after Luther, Calvin devoted his life to the ideal of building a truly Christian society based on charity, humility, and faith. For Calvin, theology was important, but it was the starting place, not the goal. His vision of a church governed by elders (in Greek, presbyteros) led to the founding of, for example, the Presbyterian Church. "Reformed" churches in Holland, Germany, and France look back to Calvinist roots.