Christianity is the world's largest religion. It is based on the life and teachings of Jesus Christ as described in the New Testament of the Bible. Most Christians believe that Jesus is the Son of God and the Messiah of the Jews as prophesied in the Old Testament (or Hebrew Bible). This is reflected in their use of the term "Christ" to describe Jesus, which is derived from the Greek translation for "Messiah". The word Christian means "belonging to Christ" or "of Christ".
Although Christianity is a monotheistic religion, most Christians believe in a God that exists as three divine persons (technically Greek hypostasis), called the Trinity. Christianity encompasses numerous religious traditions that widely vary by culture, as well as thousands of diverse beliefs and sects. Christianity is generally grouped into three main branches, which split from one another in disputes over doctrine: Roman Catholicism (the largest single denomination, with over one billion adherents), Orthodox Christianity (including Eastern Orthodoxy and Oriental Orthodoxy), and Protestantism (numerous denominations & schools of thought, including Anglicanism, Calvinism, Lutheranism, and Methodism).When combined, Christianity is the world's largest single religion, with an estimated 2.0 billion followers or about 33% of the world's population.
The vast majority of Christian religions (generally including Catholicism, Orthodox Christianity, and most forms of Protestantism, but not Restorationism) derive their beliefs from the conclusions reached by the Council of Nicea in 325 C.E., known as the Nicene Creed. This describes the beliefs that God (as a Trinity of distinct persons with one substance) became human on earth, born as Jesus pursuant to the Old Testament scriptures, was crucified by humanity, died and was buried, only to be resurrected on the third day to then rise to Heaven and "sitteth at the right hand of" (become one with) God. Christians generally believe that faith in Jesus is the only way to achieve salvation and to enter into heaven, and that salvation is a gift given by the grace of God.
Christianity originated in the first century. According to Acts 11:19 and 11:26 in the New Testament, Jesus' followers were first called Christians by non-Christians in the city of Antioch, where they had fled and settled after early persecutions in Judea. After Jesus' death, early Christian doctrine was taught by Saint Peter, Paul of Tarsus, and the other apostles. According to the New Testament Jesus was a descendant of Judah who declared himself to be the long awaited Messiah (John 8:23–24, 14:11), but was rejected as an apostate by the people generally considered to be the Jewish authorities (Matt. 26:63–64). He was condemned for blasphemy and executed by the Romans around the year 30. The formal charge cited in his execution was leading a rebellion (Luke 23:1–5): he was called the "King of the Jews" by Pontius Pilate (John 19:19–22; see Luke 16:8) on the titulus crucis or statement of the charge hung over the condemned on the cross.
The Gospels indicate that the Roman charge was actually an attempt to appease the Jewish authorities, although some scholars argue that it was an ordinary Roman trial of a rebel. According to Christians, the Old Testament predicted the death and humiliation of Jesus as recorded in the New Testament. Examples include the book of Isaiah that alludes to the slapping (Matt. 26:67–68; Isa. 50:6, 52:14–15; Mark 14:65; Luke 23:63–64), whipping (Isa. 53:5; John 19:1; Matt. 27:26) and general humiliation that is centred on the given references.
Jesus' apostles were the main witnesses of his life, teaching and resurrection from the dead, although some of the early traditions of the church name numerous disciples (as many as 70, including James Adelphos, Mark, Luke, Mary Magdalene, etc) who also followed Jesus in his travels and witnessed his miracles and teachings. After his crucifixion, his apostles and other followers claimed that Jesus rose from the dead, and set out to preach the new message. The original apostles may have written some portions of the New Testament's Gospels and Epistles; however, the four gospels are not considered to have been written eponymously by their respective namesakes.
Many of the New Testament's twenty-seven books were written by Paul of Tarsus. Twelve Epistles name him as writer, and some traditions also credit him as the writer of the book of Hebrews. The Gospel of Luke and the Acts of the Apostles are stated as having been written by Luke, whom many believe to have been under Paul's direct influence. Acts cites Paul as a student of Gamaliel (Acts 22:3), a leading figure amongst the Jewish Sanhedrin (Acts 5:34–40) and a noteworthy authority in his own right (Acts 28:16–22) considering that the Jews of Rome sought his opinion on Christianity. Paul was the principal missionary of the Christian message to the Gentile world.
There were two main communities of Christians, the Jewish Christians and the Hellenistic Christians. Jewish Christians were those Jews and Gentile converts who observed the Law of Moses (including circumcision, dietary restrictions and the concept of purity, sabbath, quartodecimanism) pejoratively called judaizing. Hellenistic Christians were those who were more influenced by the Greek-speaking world and believed that the central message of Christianity could be re-presented in ways more appropriate for Gentiles. Both these groups contributed to the New Testament and both contained within them a wide spectrum of beliefs (see J. Dunn 1977 Unity and Diversity in the New Testament).
One of the first great writers of Christianity, Tertullian, sums this up in a rhetorical address to a Roman governor with the fact that, as for the Christians of Carthage that just yesterday were few in number, now they "have filled every place among you—cities, islands, fortresses, towns, market-places, the very camp, tribes, companies, palaces, senate, forum; we have left nothing to you but the temples of your gods." (Apologeticus written at Carthage, ca. 197) Over the course of the first few centuries, classically trained theologians and philosophers such as Origen and Augustine developed Christian theology and Christian philosophy, which some argue was a synthesis of Hellenic and Early Christian thought.
During this period of first organization the Christian church had to deal mainly with occasional, but sometimes severe persecutions under Roman emperors such as Nero, Valerian, Diocletian, and Galerius. The life of the martyr, who would rather die than renounce his faith, became the highest virtue. The canonical books of the New Testament were agreed, early translations appeared, and a church hierarchy emerged: the Bishops of Alexandria, Antioch and Rome assumed the title Patriarch.
Galerius, on his death bed, signed the Edict of Galerius, allowing Christians freedom to practice their religion without hindrance (although early Christian writers like Lactantius consider Galerius the author of the last great persecution of Christians). Then, Roman Emperor Constantine I was converted in 312 and with his Edict of Milan (313) made Christianity the religion of the State. However, Rome still subjected Christians to pagan rituals. Many emperors tried to combine the God of the Christians with Mithras, the sun god, in an atempt to unite the empire under one religion. Persecution was briefly revived during the reign of Julian the Apostate (361–363) who tried to restore paganism to the empire; Christianity was later made the officially favored religion in about 382 by Emperor Theodotius. Similar events took place in neighbouring Georgia and Armenia. But in Persia, which was at constant war with Rome, the Christians struggled under the oppresive Sassanids, who tried to revive the Zoroastrian religion.
In the Persian empire, at the synod of Seleucia in 410, the bishop of Seleucia was pronounced Catholic and replaced the Patriarch of Antioch as the highest authority of the Assyrian Church of the East. Soon after, during the Nestorian Schism, this church broke all ties with the West. It would be the dominant church of Asia for more than a millennium, with bishopries as far away as India, Java, and China.
The question of Jesus's divinity was central to early Christians. A wide range of early writers, including Justin Martyr and Tertullian testify to belief that Jesus was God. At the same time, various Christian groups did not share that belief. The situation came to a head with the teaching of Arius, who brought large numbers of bishops and faithful to his belief that Jesus was a created being. The issue was settled by vote at the First Council of Nicaea, convened by Emperor Constantine I, where the teaching championed by Athanasius, trinitarianism, was enshrined as dogma (See Nicene Creed,Athanasian Creed). Although Constantine ordered all Arian books burned and Arius exiled, Arianism continued to exist and thrive in the empire for several decades, and among the Germanic tribes for almost two centuries, after the decision of the council.
This was only the first of several ecumenical councils for resolving doctrinal issues. These councils sought to unify Christianity, and were supported by the Byzantine Emperors in order to promote political stability. Some of the theological terminology of these councils may have been misunderstood by those Orthodox whose main language was Syriac, Armenian, or Coptic. As a result differences in later theological constructs lead these national branches of the church to break away from the rest, forming Oriental Churches, sometimes called the Monophysites.
By the second millennium, Christianity had spread to most of the Western world, the Middle East, parts of Africa, and had made some small inroads into the Far East as well. For the most part it had remained fairly unified in its fundamental beliefs with major theological disagreements being resolved in council. But as the millennium approached, certain major differences in theology and practice became increasingly troublesome. The Great Schism of 1054 split the Church into Western and Eastern churches: the Western church gradually consolidated under the central authority of Rome (see Catholicism), while the Eastern church adopted the name "Orthodox" to emphasize their commitment to preserving the traditions of the church and resistance to change. This Eastern Church refused to be consolidated under a single bishop, as this was completely alien to the structure the church had hitherto enjoyed. The Eastern Church recognized the Patriarch of Constantinople as the "First among equals" of the numerous bishops in charge of its autocephalous churches (see Eastern Orthodoxy).
In the European Reformation of the 1500s, Protestants and numerous similar churches renounced allegiance to Rome in objection to perceived abuses of growing Papal authority and to perceived doctrinal error and novelty in Rome. Key questions in the Reformation controversy are summed up in the famous five solas: Sola Scriptura (Scripture alone—does the church's authority derive solely from correctly interpreting the Scriptures, or does it have a separate authority?), Sola Fide (Faith alone—is a person saved through faith in Christ alone, or do the Church, good works and the sacraments contribute?), Sola Gratia (Grace alone—is a person's salvation purely and exclusively due to God's unmerited grace, or do individual works make a contribution?), Solus Christus (Christ alone—is Jesus the only mediator between humanity and God, or do the Church and its priests play a part?) and Soli Deo Gloria (Glory to God alone—does all of the glory for humanity's salvation belong to God, or are the Church and its priests eligible for a part?). The Reformation sparked a vigorous struggle for the hearts and minds of Europeans. Disputes between Roman Catholics and Protestants sparked persecution and were caught up in various wars, both civil and foreign.
Roman Catholicism and Protestantism arrived in North America (and later Australasia) with European settlement. Lacking any central authority in either Rome or national governments, Protestants worshipped in hundreds, and later thousands, of independent denominations. Protestantism was taken to South America and Africa by European colonists, especially in the 16th to 19th centuries. Orthodoxy first arrived in North America via Russian settlers in the Alaskan region in the 18th century; they came to North America from Europe in much greater numbers in the late nineteenth and early twentieth centuries. (See also Restorationism.)
In the 19th and 20th centuries many Christian-oriented nations, especially in Western Europe, became more secular. Most communist states were governed by avowed atheists, though only Albania was officially atheistic. Adherents to Fundamentalist Christianity, particularly in the United States, also perceived threats from new theories about the age of the Earth and the evolution of life.
Christianity is the world's most widely practiced religion, with 2.1 billion adherents, followed by Islam with 1.3 billion, Irreligion with 1.1 billion, Hinduism with 900 million, Chinese traditional religion with 394 million, Buddhism with 376 million, etc. Christianity has many branches, including 1.1 billion Roman Catholics, 510 million Protestants in a number of traditions, 216 million Orthodox, 84 million Anglicans, 158 million Independents (unaffiliated with the major streams of Christianity), and 31.7 million "marginals" (Jehovah's Witnesses, Latter Day Saints (Mormons), etc., these last being denominations which describe themselves as Christian but are not standardly recognized as such by other denominations due to their unorthodox teachings. Although Christianity is the largest religion in the world and there are massive missionary efforts under way, its overall rate of growth is slower than that of some other faiths and of the world population as a whole. While the population of the world grows at roughly 1.25% per year, Christianity is growing at about 1.12% per year.
Not all people identified as Christians accept all, or even most, of the theological positions held by their particular churches. Like the Jews, Christians in the West were greatly affected by The Age of Enlightenment in the late 17th and early 18th centuries. Perhaps the most significant change for them was total or effective separation of church and state, thus ending the state-sponsored Christianity that existed in so many European countries. Now one could be a free member of society and disagree with one's church on various issues, and one could even be free to leave the church altogether. Many did leave, developing belief systems such as Deism, Unitarianism, and Universalism, or becoming atheists, agnostics, or humanists.
Others created liberal wings of Protestant Christian theology. Modernism in the late 19th century encouraged new forms of thought and expression that did not follow traditional lines. Reaction to the Enlightenment and Modernism triggered the development of literally thousands of Christian Protestant denominations, Roman traditionalist splinter groups of the Roman Catholic Church that do not recognize the legitimacy of many reforms the Roman Catholic Church has undertaken, and the growth of hundreds of fundamentalist groups that interpret the entire Bible in a characteristically literal fashion.
In the United States and Europe, liberalism also led to increased secularism. Some Christians have long since stopped participating in traditional religious duties, attending churches only on a few particular holy days per year or not at all. Many of them recall having highly religious grandparents, but grew up in homes where Christian theology was no longer a priority. They have developed ambivalent feelings towards their religious duties. On the one hand they cling to their traditions for identity reasons; on the other hand, the influence of the secular Western mentality, the demands of daily life, and peer pressure tear them away from traditional Christianity. Marriage between Christians of different denominations, or between a Christian and a non-Christian, was once taboo, but has become commonplace. Some traditionally Roman Catholic countries have largely become agnostic.
Liberal Christianity grew rapidly during the early 20th century in Europe and North America, by the 1960s gaining the leadership of many of the larger US and Canadian denominations. However, this trend has reversed. At the turn of the 21st century, though secular society tends to consider the more accommodating liberals as the representatives and spokesmen of Christianity, the "mainline" liberal churches are shrinking. This is partly due to a loss of evangelistic zeal, partly due to drift of their membership to conservative denominations, and partly due to the failure of one generation to pass on Christianity to the next. Among the larger Protestant denominations in the United States, only the conservative Southern Baptist is growing. Evangelical para-church organizations have grown rapidly in the last half of the 20th century. The liberal Christian Century magazine has shrunk, while being replaced by its challenger, the rapidly growing evangelical Christianity Today.
The Enlightenment had much less impact on the Eastern Churches of Eastern and Oriental Orthodoxy. Having to face a much more hostile secular society, especially during the rise of Communism, the church clung to ancient beliefs, even as its membership eroded. Today in Eastern Europe and Russia, a renewing trend is taking place. After decades of communist-instated atheism, there is widespread interest in Christianity, as well as religion in general. Many Orthodox churches and monasteries are being rebuilt and restored, filled beyond capacity; Protestants of many denominations are pouring in to evangelize and plant churches; and the Roman Catholic church is revealing once secret dioceses and undertaking other steps to support Roman Catholic churches more openly.
In South America and Africa, Evangelical and Pentecostal Christianity form rapidly growing movements that are increasingly sending missionaries to Europe and North America. This is also true of Asia where many of the underground house churches intend to send hundreds of thousands of missionaries out over the next decade. As Modernism developed into Consumerism during the second half of the 20th century the Megachurch phenomenon developed – catering for skeptical non-Christians by providing "seeker sensitive" presentations of Christian belief. The Alpha Course can be viewed as an example one such presentation of Christianity.
Since the development of Postmodernism with its rejection of universally accepted belief structures in favour of more personalized and experiential truth, organized Christianity has increasingly found itself at odds with the desire many people have to express faith and spirituality in a way that is authentic to them. What has thus far been known as the Emerging Church is a by-product of this trend, as many people who broadly accept Christianity seek to practice that faith while avoiding established Church institutions. Another reaction of some Christians to Postmodernism is the advent of what might be called Postmodern Christianity.
A large and growing movement within the Christian church, especially in the West and most visible in the United States, is the Evangelical movement. Most mainstream Protestant denominations have a significantly active Evangelical minority, and, in some cases, a dominant majority. Evangelicals are "trans-denominational" and are more willing to have formal and informal relationships with Evangelicals from outside their denomination than to have the same sort of relationship with non-Evangelicals within their denomination.
Some Evangelicals have been schismatic within various church organisations, leaving to form their own denominations. More often they are forced out. It was only by dint of sheer determination that John Wesley, founder of Methodism, was able to remain an Anglican priest against intense opposition. His followers separated in America, and in England after his death. Some Evangelicals claim that their beliefs are no less than true Christianity itself and that those within the church who differ from them may not be true believers. This attitude has led to much disunity amongst churches, especially those with a large modernist influence. Evangelicals cannot be easily categorised, but almost all will believe in the necessity of a personal conversion and acceptance of Jesus as saviour and Lord, the eventual literal return of Christ, a more conservative understanding of the Bible and a belief in the miraculous. There are many different types of Evangelicals including Dispensationists, Reformed Christians, Pentecostals, Charismatics and Fundamentalists.