1st‑century Abrahamic religion; founder figure: Jesus of Nazareth; sacred texts: the Bible (Old and New Testaments); major branches: Roman Catholicism, Eastern Orthodoxy, Protestantism, and Oriental Orthodoxy; global adherents estimated at about 2.2 billion in 2010 (31%). According to Britannica, Christianity arose from the life, teachings, and death of Jesus and is the world’s largest religion; Pew Research Center estimates 2.18 billion Christians in 2010.

Origins and Early Development

Christianity emerged in 1st‑century Judea within the milieu of Second Temple Judaism and spread through the Roman Empire via apostolic missions, early preaching, and communal worship. As summarized by Britannica, the early church navigated questions of authority, doctrine, and worship while engaging Greco‑Roman culture and imperial power. Ecumenical councils addressed theological controversies, notably at Nicaea (325) and Chalcedon (451), where Christological and trinitarian formulations were affirmed. The Council of Chalcedon in 451 endorsed the creeds of Nicaea and Constantinople and articulated “two distinct natures in Christ,” rejecting monophysitism.

Scripture and Authority

The Christian Bible consists of the Old and New Testaments. In Western Christianity, debates over the nature of authority intensified during the Reformation, when many Protestants affirmed Scripture alone (sola scriptura) as normative for faith and practice. As noted by Encyclopedia.com, mainstream Protestantism retained core trinitarian and Christological doctrines yet diverged from Roman Catholicism and Eastern Orthodoxy particularly regarding authority and the sacraments, prioritizing the Bible over church tradition.

Doctrines and Creeds

Core Christian beliefs include the Trinity, the Incarnation, the atoning work of Christ, and the Resurrection. Philosophical analyses of the Trinity, engaging historical creeds and conciliar statements, are surveyed in the Stanford Encyclopedia of Philosophy. The Nicene‑Constantinopolitan Creed is widely accepted across traditions as an authoritative summary of faith, with its development and reception outlined by Britannica. The creed’s Western addition of the Filioque (“and the Son”) became a point of East‑West disagreement, as detailed by Britannica. The Council of Chalcedon defined Christ as one person in two natures (divine and human), a Christological standard for Catholic and Eastern Orthodox churches and a point of divergence from Oriental Orthodox churches.

Related internal links: Trinity, Nicene Creed, Reformation.

Worship, Liturgy, and Sacraments

Christian worship ranges from highly liturgical rites to non‑liturgical services, centered on Scripture, preaching, prayer, and sacraments or ordinances. In Catholicism and Eastern Orthodoxy, seven sacraments are recognized (baptism, Eucharist, confirmation/chrismation, penance, anointing of the sick, holy orders, and matrimony), as explained by Britannica. Many Protestant traditions formally recognize two dominical ordinances—baptism and the Lord’s Supper—while varying in sacramental theology, a distinction noted by Encyclopedia.com.

Related internal links: Bible, Roman Catholic Church, Eastern Orthodoxy, Protestantism.

Historical Schisms and Reformation

The gradual estrangement between Eastern and Western Christianity culminated in the East‑West Schism of 1054, marked by mutual excommunications and long‑standing theological and ecclesial differences (including the Filioque and clerical discipline), as outlined by Britannica. In the 16th century, the Reformation in northern Europe challenged medieval Roman Catholic doctrines and practices; Protestantism emerged as one of Christianity’s three major forces and later spread globally, influencing social and cultural life, according to Britannica and Britannica.

Branches and Movements

The largest Christian group is the Roman Catholic Church, alongside Eastern Orthodoxy, Oriental Orthodoxy, and the diverse Protestant traditions (including Lutheran, Reformed, Anglican, Evangelical, and Pentecostal movements). Britannica identifies these major families and notes cross‑cutting movements such as Pentecostalism and Evangelicalism. Eastern Orthodoxy emphasizes continuity with the first seven ecumenical councils and consists of territorial churches, primarily in the Balkans, Middle East, and former Soviet regions, per Britannica.

Demographics and Global Distribution

Christianity is the world’s largest religious group. A Pew study reported 2.18 billion Christians in 2010 (31% of the global population), with about half Catholic, 37% Protestant (broadly defined), and 12% Orthodox, and with adherents widely dispersed across the Americas, Europe, sub‑Saharan Africa, and the Asia‑Pacific, according to the Pew Research Center. Projections released by Pew Research Center indicate Christians remaining near 31% of the global population by 2050, with significant growth in sub‑Saharan Africa.