Christianity

Christianity is a monotheistic religion centered on the life, teachings, death, and resurrection of Jesus of Nazareth, whom adherents believe to be the Son of God and the savior of humanity. It originated among Jewish followers of Jesus in first-century Roman Judea and has since grown into the world’s largest religion by number of adherents, with practices, institutions, and theology that vary considerably across its many branches, denominations, and regions around the world.

According to Christian scripture, Jesus taught, performed miracles, and gathered a following during the early first century CE before being crucified under Roman authority. Christians believe that Jesus rose from the dead three days later, an event, the resurrection, understood as confirming his divine identity and providing the basis for salvation offered to humanity. His early followers, initially a Jewish sect, began spreading this message across the wider Roman Empire in the decades that followed, gradually developing into a distinct religious movement with its own identity, leadership, and scripture.

Scripture and Core Beliefs

Christianity’s central scripture is the Bible, comprising the Old Testament, largely shared with Judaism, and the New Testament, which records the life and teachings of Jesus along with the early history and letters of the first Christian communities. Most Christian traditions affirm the doctrine of the Trinity, holding that God exists as three persons, Father, Son, and Holy Spirit, united in a single divine being, a concept formally articulated through several church councils in the religion’s early centuries. Central to Christian belief is the idea of salvation, typically understood as reconciliation with God made possible through Jesus’s death and resurrection, accessed through faith, though different Christian traditions emphasize somewhat different roles for faith, divine grace, and good works within that overall process of salvation.

Spread and Institutional Growth

Christianity spread gradually across the Roman Empire over its first three centuries, often facing periods of persecution from Roman authorities who viewed the small, new religious movement with considerable suspicion. This changed decisively in the fourth century, when Emperor Constantine’s conversion and subsequent imperial support allowed Christianity to grow rapidly, and the Council of Nicaea in 325 CE helped formalize core doctrine, including an early statement of the Trinity, in response to theological disputes within the growing church. By the end of the fourth century, Christianity had become the Roman Empire’s official state religion, cementing its institutional power and influence across a huge swath of the ancient Mediterranean world.

Major Branches

Christianity divided into several major branches over subsequent centuries. A significant split between the Western and Eastern churches, formalized in 1054 in what is often called the Great Schism, produced the Roman Catholic Church, led by the Pope, and the Eastern Orthodox Church, which rejects papal authority over the wider church while sharing much of the same early theological heritage. The Protestant Reformation, conventionally dated to Martin Luther’s challenge to Catholic practices beginning in 1517, produced a further, much larger split, giving rise to numerous Protestant denominations that generally emphasize individual faith, scripture, and grace over institutional church authority and tradition.

Practice and Worship

Christian practice varies widely across its many branches but commonly includes regular communal worship, often on Sundays, prayer, and participation in sacraments or ordinances, rituals considered to carry particular spiritual significance. Baptism, a ritual symbolizing purification and initiation into the Christian community, and communion, a ritual meal commemorating Jesus’s last meal with his disciples before his crucifixion, are recognized in some form across nearly all Christian traditions, though the theological meaning attached to each varies considerably between Catholic, Orthodox, and the many different Protestant traditions.

The Christian calendar also structures communal religious life around major commemorations. Easter, commemorating Jesus’s resurrection, is generally considered the most theologically central Christian holiday, while Christmas, commemorating Jesus’s birth, has become the most widely observed in cultural terms, including in many societies with a large non-Christian population. Christian communities have also historically played a major role in establishing hospitals, schools, and charitable institutions in many parts of the world, reflecting a strong emphasis within the tradition on service to others alongside its specifically devotional and theological dimensions.

A Global Religion Today

Christianity today has well over two billion adherents worldwide, making it the world’s largest religion by number of followers, though the geographic center of the religion’s population has shifted considerably over the past century. While Christianity’s historical strongholds lie in Europe and the Americas, the fastest-growing Christian populations in recent decades have been in sub-Saharan Africa and parts of Asia, meaning the religion’s demographic center of gravity has moved substantially toward the Global South, even as its institutional headquarters, such as the Vatican in Rome, remain tied to its earlier European history.

FAQs

What do Christians believe about Jesus?
That he is the Son of God and the savior of humanity, who was crucified and then rose from the dead, an event confirming his divine identity and providing the basis for salvation.

What is the Trinity?
The doctrine, affirmed by most Christian traditions, that God exists as three persons, Father, Son, and Holy Spirit, united in a single divine being.

What event launched the Protestant Reformation?
Martin Luther’s challenge to Catholic Church practices, conventionally dated to 1517, which produced a major split giving rise to numerous Protestant denominations.

What happened at the Council of Nicaea?
Church leaders met in 325 CE to help formalize core Christian doctrine, including an early statement of the Trinity, in response to theological disputes within the early church.

Editorially reviewed by Specialty Digest Editorial TeamLast reviewed November 2, 2026Researched and drafted with AI assistanceReport an issue