Christianity is a monotheistic religion centered on the life, teachings, death, and resurrection of Jesus of Nazareth, whom adherents hold to be the Christ (Greek: Khristós, “anointed one”) and, in most traditions, the incarnate Son of God. It is the world's largest religion by self-identification, with an estimated 2.3 to 2.6 billion followers across every inhabited continent.(1) Christianity regards the Bible - comprising the Hebrew scriptures (Old Testament) and the distinctly Christian writings (New Testament) - as its foundational text, though traditions differ on canon, interpretation, and authority. The religion emerged in the 1st century CE from within Second Temple Judaism in the Roman province of Judea and spread rapidly throughout the Mediterranean world and beyond.

Christianity's origins are traced to the ministry of Jesus, variously estimated at approximately 26-36 CE with dates disputed, and the subsequent movement among his followers following his crucifixion under the Roman prefect Pontius Pilate. The Pauline epistles, among the earliest surviving Christian writings, predate the canonical Gospels and document the rapid spread of the faith among Gentile populations. Early Christianity was diverse, encompassing competing theological schools before a process of institutional consolidation accelerated following the Edict of Milan (313 CE) and the Council of Nicaea (325 CE). The Great Schism of 1054 CE formally divided Eastern (Orthodox) and Western (Catholic) Christianity; the Protestant Reformation of the 16th century further fractured the Western church into hundreds of distinct traditions. For a full account, see Christianity - History.

Christianity comprises three broad historical streams and thousands of distinct denominations:

• Roman Catholicism - the largest single Christian body, centered on papal authority and sacramental theology, claiming approximately 1.3 billion members.
• Eastern Orthodoxy - a family of autocephalous churches sharing common liturgical and theological heritage, dominant in Eastern Europe, Greece, and parts of the Middle East and Africa.
• Oriental Orthodoxy - pre-Chalcedonian churches (Coptic, Ethiopian, Armenian, Syriac, and others) that separated following the Council of Chalcedon (451 CE).
• Protestantism - a broad and internally diverse category originating in the 16th-century Reformation, encompassing Lutheran, Reformed, Anglican, Baptist, Methodist, Pentecostal, and many other traditions.
• Restorationism and Independent movements - traditions such as Latter-day Saints, Jehovah's Witnesses, and various non-denominational evangelical churches that arose largely in the 19th and 20th centuries.

Denominations differ on questions of authority (scripture, tradition, magisterium), sacraments, ecclesiology, soteriology, and eschatology. Some differences are treated as matters of emphasis; others have historically been considered church-dividing.

Despite internal diversity, most Christian traditions affirm a set of foundational claims: the existence of one God, the special authority of scripture, the historical reality of Jesus's life and resurrection, and the possibility of reconciliation between humanity and God through Jesus's death. Beyond this core, significant doctrinal variation exists. Trinitarian theology - the teaching that God exists as Father, Son, and Holy Spirit - is shared by Catholic, Orthodox, and most Protestant bodies but rejected by Unitarians and some restorationist groups. The nature of the Eucharist, the role of Mary, the mechanics of salvation, the structure of church governance, and the interpretation of biblical prophecy are among the most contested internal questions.

Christianity has historically shaped law, ethics, political philosophy, art, architecture, music, and social institutions across large portions of the globe. Its relationship to secular governance, scientific inquiry, and other religious traditions is the subject of ongoing debate both within and outside the religion. Questions about Christianity's social role - including its historical involvement in colonialism, slavery, and the Crusades, as well as its contributions to education, abolition, and civil society - remain contested. See Christianity - Debate for major disputed questions.

Mainstream historical scholarship holds a broad consensus on the existence of Jesus as a historical figure and on the general outline of early Christianity's development. See Christianity - Historical Consensus. The theological claims of Christianity - including the resurrection and the divine status of Jesus - are not evaluated by historical or scientific consensus, as they fall outside the domain of empirical inquiry; these remain matters of religious viewpoint.

• Traditional Christian orthodoxy - holds Christianity's doctrinal claims to be literally and historically true. Orthodox Christian Viewpoint
• Liberal/progressive Christianity - reinterprets traditional doctrines in light of contemporary scholarship, ethics, and experience, often de-emphasizing supernatural claims. Progressive Christian Viewpoint
• Secular and non-Christian perspectives - range from respectful cultural assessment to active criticism of Christianity's truth claims and historical record. Secular Viewpoint
• Interfaith perspectives - Jewish, Islamic, and other religious traditions have distinct and sometimes sharply divergent assessments of Christian claims, particularly regarding Jesus's identity. Interfaith Viewpoint

• Christianity - History
• Christianity - Debate
• Christianity - Historical Consensus
• Religion
• Judaism
• Islam
• Jesus of Nazareth
• The Bible
• Protestant Reformation
• Council of Nicaea
• Secularism

1. Pew Research Center figures report self-identified Christians; the original estimate of 2.3-2.6 billion reflects self-identification rather than active practice. Pew Research Center. Global Christianity: A Report on the Size and Distribution of the World's Christian Population. Pew Research Center, 2011. Updated estimates in subsequent reports through 2024.
2. Crossan, John Dominic, and Jonathan L. Reed. In Search of Paul. HarperSanFrancisco, 2004.
3. Ehrman, Bart D. Lost Christianities: The Battles for Scripture and the Faiths We Never Knew. Oxford University Press, 2003.
4. MacCulloch, Diarmaid. Christianity: The First Three Thousand Years. Viking, 2010.
5. Pelikan, Jaroslav. The Christian Tradition: A History of the Development of Doctrine. 5 vols. University of Chicago Press, 1971-1989.
6. Meier, John P. A Marginal Jew: Rethinking the Historical Jesus. 5 vols. Yale University Press, 1991-2016.