The term Christianity, having various nuances or senses of meaning, always refers to the entire population, past and present, of 'Christians'; people who believe, or profess to believe, wholly or fundamentally, in the teachings of a man called Jesus Christ, or Jesus of Nazareth, who lived some two thousand years ago in Palestine. The religious community that emerged during Jesus' lifetime and following his death today comprises the most populous religious community in the world, consisting of over two billion Christians, approximately one-third of the world's population.
A numerous and varied set of traditions have evolved from the first-century philosophy and teachings of Jesus Christ, as recorded in the New Testament, rendering Christianity a community of differing religious groups with distinct organizational structures, rituals and ceremonies, and interpretations of its founders teachings. As Jesus grew up in the Jewish tradition, Christianity arose as an historical and theological offspring of Judaism, wherein the early Christian community incorporated Jewish religious writings as its Old Testament, along with its Jesus-based New Testament, to construct its Christian Bible. The relationship between the Jewish and Christian traditions remains complex and multifaceted. Like Jews, Christians believe in the existence of a single God, but unlike Jews, most Christians belong to churches that teach that God comprises three 'persons' sharing a single Godhead — a teaching referred to as Trinitarianism.
Christians believe that God has revealed his expectations, or 'will', for humanity in the Christian Bible, the writing of which He inspired.
Origins and history of Christianity
These have been summarized for different types of Christianity as follows:
- Orthodox: church, tradition, liturgy
- conservative Catholic: church, tradition, Pope
- Protestant, formerly: scripture, church
- liberal (Catholic and Protestant): reason, experience
- charismatic (Catholic and Protestant): Holy Spirit, scripture
- evangelical Protestant: scripture
Christian doctrine is largely based upon several core beliefs:
Christianity is monotheistic; that is, Christians believe in one God, who is in three persons, the Father, Son, and Holy Spirit. This God is understood to be identical to the Jewish understanding of God in the earlier portions of the Bible. Christianity asserts that God is ethically perfect, or holy, and that God is immutable; that is, God does not change.
Christians believe that Jesus was the Son of God; the mainstream belief is that he was the second person within the Trinity and that he was both fully human and fully divine; he is considered to be God incarnate on the Earth.
Soteriology is the theology of salvation. Mainstream Christians believe that, as a result of the fall of Adam and Eve, all humans are sinful. Because of this "sinful nature", all people are not in a proper relationship with God, possibly doomed to be condemned to Hell for breaking God's command.. However, Christian soteriology asserts that Christ came to Earth as a human being, and was crucified to take the punishment for man's sin. Mainstream Christians believe that a person must accept God's forgiveness, and if they do so, that they are allowed to go to heaven.. Most Protestants today agree that salvation is "by grace alone", meaning that a person is not required to do good works to get into heaven, although good works will generally be a by-product of salvation.
Eschatology is the study of "last things," or beliefs about the end of the world and the afterlife. Christians believe that after Christ was crucified, he was resurrected from the dead (the origin of the celebration of Easter), that he ascended to Heaven, and he will return to Earth.
There is disagreement among Christians about how eschatological prophecy should be interpreted, particularly about when Christ will return to Earth and whether the book of Book of Revelation is primarily about past, current, or future events, and whether certain parts should be interpreted as metaphor or literal event.
Some Christians adopt a preterist interpretation of eschatological Biblical prophecies, and contend that the events described in the Book of Daniel, chapter 7 and the Book of Revelation were mostly or all fulfilled in the 1st Century. Other Christians adopt a futurist interpretation and contend that these events are yet to take place. In addition to the preterist and futurist view, the premillennialism school of thought, strongest in the 21st century among fundamentalists and evangelicals, holds that the second coming of Christ precedes and ushers in the millennium (the thousand years mentioned in Revelation 20 during which holiness is to be triumphant and Christ is to reign on earth). They argue that it can come at any moment, with portends indicating it may come soon. This position downplays social action because nothing mankind can do will hasten the Second Coming.
In opposition the postmillennialism position holds that the second coming of Christ will be after the millennium which is to come as the result of the Christianization of the world without miraculous intervention. This position strongly encourages Christians to reform the world in order to hasten Christ's coming. Postmillennialism was a major source of social activism among Christians in the 19th and early 20th centuries, including the Second Great Awakening, the abolitionist movement, the Third Great Awakening and the Social Gospel movement. Mainstream Protestant denominations after 1920 downplayed the Second Coming.
A recurring theme in the history of Christianity is that, in every age, there are Christians who believe that the eschatological pronouncements of the Bible apply to their lifetimes or to the not-too-distant future. This was noted also among the earliest Christians: In 1 Corinthians 7, the apostle Paul urges his followers not to worry too much about their present state of affairs: "I mean, brothers and sisters, the appointed time has grown short... For the present form of the world is passing away" (1 Cor. 7:29-31, trans. NRSV)-- a statement taken by some scholars to mean that Paul, and his followers, believed the return of Christ (and perhaps the end of the world) was imminent.
Christian doctrine is practiced in a number of ways:
Creeds are concise statements of belief. Creeds in Christianity originated as confessions of faith given by those preparing for baptism to show that the catechumen had become familiar with and accepted the truth of its doctrines, and evolved into being free-standing summaries of Christian belief. Nowadays, creeds are used as part of the liturgical worship of some denominations.
The main ancient creeds in Christianity are the Nicene Creed, Apostles' Creed and Athanasian Creed. Other Christian creeds include the Augsburg Confession (used by the Lutheran Church), the Belgic Confession, the Cambridge Declaration (written in 1996 by the Alliance of Confessing Evangelicals), the Canons of Dort, the Chalcedonian Creed (451's Council of Chalcedon), the Helvetic Confessions (created in 1536 by the Swiss Reformed Church), the Orthodox Confession, the Racovian Catechism (1605) and the Westminster Confession.
Some Christians reject the concept of creeds and instead believe in the sole sufficiency of the Bible itself. With careful study, the devout Christian can determine for themselves what to believe and how to act within and without the church. This concept, called "sola scriptura" is considered one of the theological pillars of the Reformation. Sola scriptura (Latin ablative, "by scripture alone") is the doctrine that the Bible is the only infallible or inerrant authority for Christian faith, and that it contains all knowledge necessary for salvation and holiness. Consequently, Sola Scriptura demands that no doctrine is to be admitted or confessed that is not found directly or logically within Scripture.
Christians pray for a variety of reasons - for forgiveness when they sin, to ask for help or guidance (known as petitionary prayer), as a meditative practice, to demonstrate respect and reverence and because for many it feels comforting and enjoyable to spend time in communication with God. There are a variety of different prayers used by Christians - the main being the Lord's Prayer, a portion of the Sermon on the Mount that Jesus commands his followers to use in Matthew 6:9-13 and Luke 11:2-4. The Lord's Prayer is used by almost all Christian denominations, although the exact wording can differ slightly.
Hermeneutics addresses the art and theory of understanding and interpreting of linguistic and non-linguistic expressions. The hermaneutic tradition dates from ancient Greek philosophy. During the Middle Ages and the Renaissance, hermeneutics was developed as an aspect of Biblical studies. It has also developed as the study of ancient and classic cultures.
Cataphatic theology addresses what is known about God, what is known to be and how God is known to act within the context of a religion's dogmatic and ethical precepts. " . . . the role of cataphatic theology is to articulate anything that can be conceptualized about God."
Apophatic theology or negative theology (apophasis) addresses God from the standpoint of what can not be said about God and the nature of God.
Dogmatic theology is the study of the stated truths of a religion.
Moral theology addresses the practical acts and the truth of morality. In this sense it is the ethics of a religion which in turn is the study of the morality or acts of a religion.
Pastoral Theology addresses the care of religious adherents, the care of their souls, in the context of the beliefs and morals of that religion.
Mystical theology addresses the state of the soul or spirit and acknowledges the imperfect ability or complete lack of the ability of the empirical investigation of such phenomena.
Liberation theology was begun in South America to address social injustices. The church was to align itself with the poor and by questioning and acting to remediate such problems as poverty and discrepancies in the judicial systems that favoured one class above another.
Romanticism was a search for feeling and an exploration of the inner soul. Nowhere was this more true than in theology, where the German theologian Friedrich Schleiermacher (1768–1834) reshaped liberal Protestant thought. Traditionally theologians pondered the infinity and omnipotence of God. That was less relevant, argued Schleiermacher, than the inner feeling of a person of absolute dependence upon God, and the intuition of God's presence. Blessedness, he taught, consists in the strengthening of the God-consciousness through the community of believers (the Church); sin is the obscuring of this consciousness. Jesus Christ shared the humanity of all human beings but was unique in the strength and constancy of his God-consciousness.
Postmodern theology or in fact, anything to which the term ‘postmodern’ is affixed does not define a school of beliefs or a set of defined precepts recognizable as truisms. Postmodernism is an approach or a practice that seeks to be critical and employ comparisons and differences to deconstruct or destabilize certainty. This view or approach makes the theology of numerous religious perspectives a prime target.
Postmoderism primarily rejects the idea of objectivity, there are no descriptions of definitions that are neutral. In this sense, any postmodern field of study is basically saying that field is without objectivity, without certainty, everything is open to interpretation. 
Twentieth century theology saw numerous 'liberal' drifts - the German theologian Rudolf Bultmann (1884-1976) was an influential writer in this line - using form-criticism to develop a skeptical approach to the New Testament, and seeking to "demythologize" the texts and the theologies depending on them. New Testament scholarship also saw new attention through the often skeptical lens of the Jesus Seminar, whose members often drastically reunderstood the Biblical stories about Christ, some even doubting the existence of Christ altogether.
Don Cupitt pushed for a 'post-God' theology, seeing faith as a human construct and rethinking religious practice around this belief. This was part of what many called the Death of God theology movement (a reference to the famous remark by nineteenth century German philosopher Friedrich Nietzsche). Following Ludwig Wittgenstein, many philosophers and theologians reinterpreted religious language as anti-realist, purely ethical or personally transformative. Postmodern theology sprung up, along with theologies of identity and liberation: feminist theology, queer theology and liberation theology (the latter a movement within Catholicism by theologians like Gustavo Gutiérrez working among the poor in South America) - these theologies tying religious ideas to political and theoretical movements of the time. Theology also veered more towards being driven by dialogue with less claims to universal truth.
Karl Barth reacted against 20th-century liberal thought and the innerness of God, and insisted on God's transcendence. Barth stressed the discontinuity between the Christian message and the world. God is the wholly other, He is known only in His revelation, and He is not the patron saint of culture, but its judge.
Logical positivism was a school of thought which came about through a number of developments in the early years of the 20th century. Basically, logical positivism denied the truth of any statement (and thus any belief) that was not capable of verification. Metaphysics was unacceptable and this rejection was couched in the strongest terms. The impact of logical positivism on theology has been profound primarily through the rejection of religious beliefs even though the basic tenants of logical positivism have been subjected to a great degree of mitigation - truth is only that which is verifiable is not now considered to be verifiable.
Christianity has developed into a variety of traditions and ecclesiastical bodies over the past 2,000 years. The broadest division is between Eastern and Western Christianity, two families that come from historical differences between the the Greek-speaking Byzantine Empire and Latin-speaking Roman Empire. The Eastern traditions are primarily made up of the Eastern Orthodox Church and the Oriental Orthodox Church, two associations of national churches in communion (although not usually with one another.) The Western faiths trace their heritage through direct descent, Reformation, or missionizing from the Roman church and include Catholicism, Protestantism, and Anglicanism, as well as a variety of splinter groups such as the Mormons.
In addition, there are hundreds of millions of independent Christians - many in the United States; sub-Saharan Africa, where the Pentecostal movement has been influential; and in mainland China - that have a legacy of some Protestant history, but are not formally associated with a church authority. Some churches from the East have formally joined the Catholic faith, and are historically and culturally Eastern, but ecclesiastically Western.
The Eastern Orthodox Church is made up of approximately 17 national churches - the numbering can differ depending on one's perspective on the Orthodox Church in America. These national churches are all in communion with one another and none of them have any ecclesiastical authority over one another, although they all recognize the special place of the Ecumenical Patriarch of Constantinople as primus inter pares or "first among equals." These independent churches are called autocephalous and several smaller churches are autonomous and under the authority of autocephalous bodies.
Eastern Orthodoxy and Roman Catholicism gradually evolved into two distinct churches. Historians do not regard any one event in the process as definitive. The differences between the two bodies built up over centuries: the East used Greek as a liturgical language, the West used Latin; Easterners emphasized monasticism, mysticism, and negative theology (apophasis) to experience God, whereas Westerners focused on rationalistic explanations and formalized doctrines.
The Oriental Orthodox Church is more loosely affiliated culturally than the Eastern Orthodox, but the role of the Coptic Pope is stronger ecclesiastically than the Ecumenical Patriarch. The Oriental Orthodox gradually ceased to be in communion with the rest of Christianity as a result of the Council of Chalcedon in 451 and the resulting Chalcedonian Creed which established a particular formula for understanding how Jesus can be both divine and human in full measure. The Christology of the Orientals has been labeled monophysite, but the Church defines itself as miaphysite - the differences go back to the original Christological controversy of the fifth century, with the former denying that Jesus had any substantial human nature. Similar to the Easterners, Orientals use icons in worship, have a strong monastic tradition, and have focused on the lives of saints for spiritual guidance.
The Assyrian Church of the East, i.e. the church in the Persian Empire, declared itself independent of "Western" church authorities, i.e. those in the Roman Empire, in 428. It evolved a distinct theology after the Council of Ephesus in 431, a gathering of Christians to combat the heretical group lead by Nestorius, leading to charges that the Assyrians were themselves Nestorians. In the mid-sixteenth century, several churches broke communion with the Patriarch of Babylon, spiritual head of the Church of the East and joined into communion with the Catholic Church becoming the Eastern Catholic Chaldean Rite. Due to political instability in Iraq and Assyrian immigration, the church is headquartered in Chicago, the United States.
While the Latin Rite of Catholicism makes up over 98% of the believers in the Catholic Church, there are about 20 Eastern Rites which are allowed to conduct their own liturgy and maintain many of their own distinct practices, such as married priests, while acknowledging the primacy of the Bishop of Rome, as an authoritative head to their church as well.
Catholicism is the largest denominational family amongst Christians, and the Roman Catholic Church is the largest institution of any kind on the face of the Earth, largely due to missiological efforts in Latin America. In addition to believers who are the product of Portuguese and Spanish colonialism, Catholicism has a strong history in Western Europe, where it remained virtually the sole church in the West from the time of the Schism through the Reformations of the 15th and 16th centuries.
The Catholic Church is united by several distinct traditions, possibly the most important of which is the Pope - Bishop of Rome and the monarch of Vatican City. The Pope's ecclesiastical see is known as the Holy See and is given a priority in terms of both honor and authority amongst all other Catholic bishops. Catholics have rich traditions of doctrine, canon law, sainthood, and sacred architecture.
Protestantism is not a single church body or set of formally-related organizations, but a grouping of various church families whose history extends to the Reformations in 16th century Europe. The main families are the Lutheran, the Reformed and Presbyterians, and the Anabaptists. Protestantism has spread as widely across the globe as has Catholicism, and has developed into a wide variety of national expressions as well as being foundational in international ecumenical movements such as the World Council of Churches.
Certain pre-Reformation groups are frequently included in discussions about Protestantism, such as Waldensians and Moravians, who are legacies of reformation movements lead by Peter Waldo in 12th-century Italy and Jan Hus in 15th-century Bohemia. Some classification systems also include Anglicans as well, as the Church of England and the Roman Catholic Church ceased to be in communion roughly concurrent with the Reformation and the Church of England accepts many Protestant doctrines. Since the Reformation, large Protestant groups include Baptists, Methodists, the Churches of Christ, Disciples of Christ, and Adventist churches that come from the Restorationist movement of mid-18th century America.
The Mormons, Jehovah's Witnesses, and Christian Science originated in the 19th century U.S. Depending on the definition of what constitutes Christianity, those movements may not even be considered Christian due to their unique understandings of virtually every Christian doctrine.
Anglicanism is a form of Christianity with elements of both Protestantism and Catholicism. The Anglican Church was formed by Henry VIII at roughly the same time as the self-definition of Protestantism, and there are some commonalities between Protestantism and Anglicanism. The Church of England ceased to be in communion with Rome as a result of Henry's actions and his insistence that the King of England be head of the English church. Anglicanism evolved under Elizabeth I as a via media or middle way. The emphasis on ritual and liturgy in the Roman Catholic Church is also found, to some extent, in the Anglican Church. Anglicans also stress the common lineage their clergy have with Catholics - a doctrine known as apostolic succession, which ties present-day religious workers with the original twelve apostles of Jesus. Rome, however, does not recognize Anglican orders as valid.
Anglicans organise into national churches, all of which participate in the Anglican Communion, which is headed by the Archbishop of Canterbury. Currently, there is significant controversy in the Anglican Communion over the ordination of gay and female clergy, with many of the conservative churches in Africa refusing to participate in the 2008 Lambeth Conference and instead participating in the Global Anglican Futures Conference (GAFCON) in Jerusalem.
Some churches that do not identify with any denomination. Charismatic Christianity and Pentecostalism are two similar movements founded in the twentieth century which prioritize an individual's experience of God through the Holy Spirit, including the reception of spiritual gifts such as glossolalia, spiritual healing, and prophecy. Charismatics have generally stayed within their original church bodies, whereas Pentecostals have created their own denominations and separate churches. These bodies are particularly prevalent in Africa.
Evangelicalism is another movement that exist both with established church groups and entirely independent churches, some of which have evolved out of small house churches and private Bible study groups into larger networks of churches, particularly in America. Evangelicals are similar to fundamentalists in some of their emphasis on the priority of the Bible, but are not as hostile to modernity nor mainstream politics. They have also been associated with a Social Gospel in their insistence on providing services to underprivileged populations, particularly through missions work.
Both of these movements are Western although they have typically do not have formal ties to other historically Western churches.
Unitarianism is a movement that developed out of Protestant Christianity and rejects the concept of the Trinity. It developed in Poland and Transylvania in the 1560s, and spread to England in the seventeenth century and from there on to the United States. Unitarians place emphasis on the role of reason in reading the Bible, and many early Unitarians rejected concepts like original sin. The Unitarian Universalists combined this with a belief that everybody is saved. Unitarianism today draws inspiration from a variety of sources, often combining religious and secular sources of inspiration, and practicing a very open and tolerant worship service welcoming gays and lesbians, and advocating for social change.
Another important cross-denominational movement in the 20th century has been ecumenism: a cooperation of Christian bodies that can be as simple as coordinating common efforts in social services, writing common theological statements, the restoration of communion between bodies, and even the creation of entirely new denominations themselves, such as the Uniting Churches. The World Council of Churches (WCC) is an international body whose membership includes a majority of the Christian world if one includes Catholicism (the Roman Catholic Church is not a member of the WCC, but works with it closely on several initiatives.) The National Council of Churches is an American equivalent that has similar goals as the WCC.
See the detailed guide on the Bibliography subpage
- Brauer, Jerald C. The Westminster Dictionary of Church History (1971), 880pp
- Briggs, J. H. Y., Robert D. Linder, and David F. Wright. Introduction to the History of Christianity: First Century to the Present Day (2006) excerpt and text search
- Cross, F. L., and E. A. Livingstone, eds. The Oxford Dictionary of the Christian Church (3rd ed. 1997), 1840pp; excerpt and text search; online at OUP
- Hastings, Adrian et al. eds. The Oxford Companion to Christian Thought (2000) 808pp; 600 articles by 260 Catholic, Protestant and Orthodox scholars; excerpt and text search; online at OUP
- Horsley, Richard A. Christian Origins: A People's History Of Christianity, Vol. 1 (2006), 318pp excerpt and text search
- Latourette, Kenneth Scott. A History of Christianity (2 vol 1975) excerpt and text search vol 1, to 1500
- McGonigle, Thomas D., and James F. Quigley. A history of the Christian Tradition: From Its Jewish Origins to the Reformation (1988); A History of the Christian Tradition, Vol. II: From the Reformation to the Present (1996) excerpt and text search vol 2
- Noll, Mark A. The Old Religion in a New World: The History of North American Christianity (2001) excerpt and text search
- Ward, Keith. Christianity: A Beginner's Guide (2008)
- Johnson, Todd M.; Barrett, David B.; Kurian, George Thomas (2001). World Christian encyclopedia: a comparative survey of churches and religions in the modern world. Oxford [Oxfordshire]: Oxford University Press. ISBN 0195079639.
- Woodhead, Religions in the Modern World, Routledge, 2002, page 157
- Theologians quote James 1:17, "the Father of lights, with whom is no variableness, neither shadow of turning." See Charles Hodge, Systematic Theology (1873) p. 390 online
- Theologians cite Romans 3:23 "for all have sinned and fall short of the glory of God" (New International Version).
- Theologians cite Romans 10:9-10 "That if you confess with your mouth, "Jesus is Lord," and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you confess and are saved."
- cf. Paul, by E.P. Sanders, Oxford University Press, 1991, p. 32 ff.
- Ramberg, Bjørn and Gjesdal, Kristin, "Hermeneutics", The Stanford Encyclopedia of Philosophy (Summer 2009 Edition), Edward N. Zalta (ed.), Hermeneutics
- Chirban, John (2005)(Orthodox Theologic Roots of Holistic Healing Orthodox Christian Assoc. of Medicine Psychology and Religion, Vol III, no. 2
- Boesel, Chris and Catherine Keller (Eds) (2009). Apophatic Bodies Negative Theology, Incarnation, and Relationality excerpt Fordham University Press.
- BBC (2009). Liberation Theology
- Peter Heltzel, "Friedrich Schleiermacher: The Father of Modern Protestant Theology," (1998) online
- Vanhoozer, J. K. (Ed) (2003) “Theology and the conditions of postmodernity - A report on knowledge (of God)” in The Cambridge companion to postmodern theology. Cambridge University Press; Aylesworth, Gary, "Postmodernism", The Stanford Encyclopedia of Philosophy (Winter 2010 Edition), Edward N. Zalta (ed.), 
- George Pattison (1998) The End of Theology - and the Task of Thinking About God, London: SCM Press
- See, for instance, the chapters fifteen and nineteen in Paul Kurtz, Vern L. Bullough and Timothy J. Madigan (eds.) (1994) Toward a New Enlightenment: the philosophy of Paul Kurtz, New Brunswick and London: Transaction.
- Robert H. King, "Models Of God's Transcendence," Theology Today 23#2 (July 1966 p 200+; see also Charles Hodge, Systematic Theology (1873) p. 395 online
- Shalizi, Cosma Rohilla (2004) Dept. of Statistics, Carnegie Mellon University Logical Positivism