Christianity

• 1. Introduction

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  Christianity counts more than 2.3 billion followers, roughly 28.8% of the world's population, making it the largest and most widespread religion on Earth. Its adherents form a majority in 120 countries and territories. Yet it began as something far smaller. In the 1st century, in the Roman province of Judaea, a Jewish movement formed around a man his followers believed had risen from the dead. They did not think they were founding a new faith. They thought they were waiting for him to return. How did a community in Jerusalem that expected the world to end become a religion spanning Europe, Africa, Asia, and the Americas? Why did it split from Judaism, then split again and again within itself? And what does it actually teach about the man at its center, who his followers call God the Son, the Logos made flesh, who died on a cross and rose for the salvation of humankind? This message has a name. It is called the gospel, which means the good news.

• 2. A Name In Antioch

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  Early Jewish followers of Jesus did not call themselves Christians. They referred to themselves as being of 'The Way,' an expression possibly drawn from Isaiah 40:3, "prepare the way of the Lord." The word that would later define them was first applied by outsiders. According to Acts 11:26, the term "Christian," meaning "followers of Christ," was first used in the city of Antioch by the non-Jewish inhabitants there. The name pointed back to Jesus and his disciples. The label for the faith itself came a little later. The earliest recorded use of the word "Christianity" was by Ignatius of Antioch around 100 AD. Even the founder's name carried this layering of languages. Jesus comes from the Greek Iesous, probably rooted in the Hebrew form. From the start, this was a movement named in Greek by Gentiles, about a Jewish teacher, in a city far from where he had lived.

• 3. Breaking From Judaism

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  The earliest followers of Jesus were Jews who understood his life and expected return through familiar Jewish apocalyptic and messianic frameworks. They remained embedded in Jewish religious life. This first community in Jerusalem awaited Jesus's return and was led by three figures known as the Pillars of the Church: James the Just, Peter, and John. What became of them is unclear. They were possibly displaced, relocated, or killed when the Romans destroyed Jerusalem in 70 AD. As the message spread into the broader Greco-Roman world, it attracted Gentiles, especially "God-fearers" who took part in synagogue worship without fully converting. Paul the Apostle, a Jew of the Pharisaic school who had first persecuted the Jesus movement, became one of its most influential missionaries after his conversion. Paul argued that Gentiles could share in the promises of Israel through faith in Christ, baptism, and devotion to the God of Israel, without full adherence to the Torah, including circumcision. This had a formative effect on a Christian identity separate from Judaism. The inclusion of Gentiles led Christianity to slowly separate from Judaism in the 2nd century.

• 4. Heretics And Church Fathers

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  From the year 150, Christian teachers began producing theological and apologetic works to defend the faith. These authors are known as the Church Fathers, and their study is called patristics. Notable early figures include Ignatius of Antioch, Polycarp, Justin Martyr, Irenaeus, Tertullian, Clement of Alexandria, and Origen. During this period there was no unified movement, but multiple competing sects holding radically different beliefs. Christian authors began using the Greek term hairesis, meaning "school of thought," to describe rival communities, and from this came the concept of heresy. Valentinus, an Alexandrian teacher, developed a Gnostic theology in which Christ brought saving knowledge, or gnosis, that freed believers from the material world. Marcion, from Sinope, drew a distinction between a high, purely good god, father of Christ, and the lower, merely "just" god of Israel. Marcion also assembled a collection of Christian texts, including his own gospel, creating one of the earliest known Christian scriptural canons. Justin Martyr, from Neapolis, disagreed with both, arguing that the God of the Jewish scriptures was Christ himself before his incarnation.

• 5. Empire And Persecution

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  Tacitus wrote that Emperor Nero blamed Christians for the Great Fire of Rome in 64 AD. In antiquity, religion was bound up with ancestral tradition and ethnic identity, so Gentile Christians who rejected their native gods were seen as disrupting the bond between the divine and the community. Before the mid-3rd century, persecutions were often reactive, sporadic, and local. This changed in 249, when the emperor Decius ordered all residents of the empire, except Jews, to perform a sacrifice to the Roman gods. Jews had long been excused on the basis of ancestral custom, a protection Christians lacked. The Diocletianic Persecution beginning in 303 was particularly severe, bringing confiscations, destruction of buildings, expulsions, imprisonment, and demands for sacrifice. The situation changed under Constantine, who granted imperial support to Christianity, though heretical forms were suppressed under him and his successors. State-sanctioned persecution ended with the Edict of Toleration in 311 and the Edict of Milan in 313. At that point Christianity was still a minority belief, perhaps only 5% of the Roman population.

• 6. From Nicaea To Schism

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  In 325, Constantine convened the First Council of Nicaea, which sought to address Arianism and formulated the Nicene Creed, still used in Catholicism, Eastern Orthodoxy, Lutheranism, Anglicanism, and many other Protestant churches. Nicaea was the first of a series of ecumenical councils that defined critical elements of theology, especially Christology. On the 27th of February 380, Theodosius I, Gratian, and Valentinian II issued the Edict of Thessalonica, establishing Nicene Christianity as the state church of the Roman Empire. Once tied to the state, the Church grew wealthy, soliciting donations from the rich and owning land. The unity did not hold. The Church of the East did not accept the third and later ecumenical councils and remains separate today through the Assyrian Church of the East. The Church of the East and Oriental Orthodoxy both split over differences in Christology during the 5th century. The Eastern Orthodox Church and the Catholic Church separated in the East-West Schism in 1054, disagreeing on administrative, liturgical, and doctrinal issues, most prominently Eastern Orthodox opposition to papal supremacy. Later attempts at reunion, at the Second Council of Lyon in 1274 and the Council of Florence in 1439, failed when the Eastern Orthodox refused to implement the decisions.

• 7. Reformation And Reach

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  During the Reformation, Martin Luther posted the Ninety-five Theses in 1517 against the sale of indulgences, and printed copies soon spread throughout Europe. In 1521 the Edict of Worms condemned and excommunicated Luther and his followers, splitting Western Christendom into several branches. Reformers like Zwingli, Oecolampadius, Calvin, Knox, and Arminius further criticized Catholic teaching, and these challenges grew into Protestantism, which rejected the primacy of the pope, the role of tradition, and the seven sacraments. The Reformation in England began in 1534, when King Henry VIII declared himself head of the Church of England. Beginning in 1536, the monasteries throughout England, Wales, and Ireland were dissolved. Partly in response, the Catholic Church engaged in reform known as the Counter-Reformation, and the Council of Trent reasserted Catholic doctrine. The discovery of America by Christopher Columbus in 1492 brought a new wave of missionary activity. Following the Age of Discovery, Christianity expanded globally through missionary work, evangelism, immigration, and trade, reaching the Americas, Oceania, East Asia, and sub-Saharan Africa. Division also brought violence, including the Thirty Years' War, the English Civil War, and the French Wars of Religion.

• 8. What Christians Believe

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  The central tenet of Christianity is belief in Jesus as the Son of God and the Messiah, anointed by God as savior of humanity. Christians hold that through belief in and acceptance of the death and resurrection of Jesus, sinful humans can be reconciled to God and offered salvation and the promise of eternal life. Generally, Christians believe Jesus is "true God and true man," fully divine and fully human, who suffered the pains and temptations of a mortal man but did not sin. The resurrection is considered the cornerstone of the faith. According to the New Testament, Jesus was crucified, buried, and rose from the dead three days later, appearing afterward to his apostles and to "more than five hundred brethren at once" before his ascension to heaven. Paul the Apostle wrote, "If Christ was not raised, then all our preaching is useless, and your trust in God is useless." Closely linked is the doctrine of the Trinity, the teaching that one God comprises three distinct, eternally co-existing persons: the Father, the Son, and the Holy Spirit. In the words of the Athanasian Creed, "the Father is God, the Son is God, and the Holy Spirit is God, and yet there are not three Gods but one God." The Greek word trias appears in this sense first in the works of Theophilus of Antioch.

  Justin Martyr described 2nd-century Christian worship in his First Apology, written around 150 to Emperor Antoninus Pius, and his account still maps onto the basic structure of Christian liturgy. He wrote that on Sundays believers gather, the memoirs of the apostles or the writings of the prophets are read, the president instructs and exhorts, prayers are offered, and bread, wine, and water are brought and shared, with portions sent to the absent and collections given to orphans, widows, and the sick. Nearly all forms of worship incorporate the Eucharist, reenacted following Jesus's instruction at the Last Supper, where he gave his disciples bread saying, "This is my body," and wine saying, "This is my blood." Baptism is the ritual act, using water, by which a person is admitted to membership of the Church, practiced by immersion, submersion, affusion, or aspersion. The cross was used by Christians from the earliest times, though the crucifix did not appear until the 5th century. Among the earliest symbols, the fish, or Ichthys, ranked first in importance, its Greek letters forming an acrostic for the phrase "Jesus Christ, Son of God, Savior."

  For the last hundred years, the Christian share has held at around 33% of the world population, but that stability hides a major shift. Large increases in the developing world have come alongside substantial declines in the developed world, mainly in Western Europe and North America. Today 46.8% of the Christian population is concentrated in 10 countries, led by the United States with over 210 million, Brazil with over 160 million, and Mexico with over 110 million. The three main branches are Catholicism with 1.3 billion people, Protestantism with 800 million, and Eastern Orthodoxy with 300 million, alongside Oriental Orthodoxy with 60 million and Restorationism with 35 million. Since 1900, Christianity has spread rapidly in the Global South, and the West is no longer the chief standard bearer of the faith. From 1960 to 2000, the global growth of reported Evangelical Protestants ran three times the world's population rate, and twice that of Islam. According to the historian Geoffrey Blainey, since the 1960s there has been a substantial increase in conversions from Islam to Christianity, mostly to Evangelical and Pentecostal forms. By 2050, the Christian population is expected to exceed 3 billion, with Pew Research Center projecting 1.1 billion African Christians alone.