Christianity: Jesus, the Bible and Core Doctrines

Christianity is the world's largest religion, with approximately 2.4 billion adherents worldwide. It emerged in 1st-century Palestine from within Judaism, centred on the figure of Jesus of Nazareth, whom Christians believe to be the Messiah and Son of God. From small beginnings as a Jewish messianic movement, it became the official religion of the Roman Empire by the 4th century and has since spread across the world.

This lesson covers the historical Jesus and the formation of the early church, the structure of the Christian Bible, and the central doctrines that have crystallised over two millennia.

The Jewish background

Christianity cannot be understood apart from its Jewish background. Jesus and his earliest followers were Jews, observing Jewish law, worshipping in synagogues and the Temple, and engaging Jewish messianic expectations.

By the 1st century CE, Jewish religious life included:

• The Pharisees — focused on the application of Torah to everyday life; the eventual ancestors of rabbinic Judaism.
• The Sadducees — the priestly aristocracy associated with the Temple.
• The Essenes — an ascetic community (perhaps including the Qumran community of the Dead Sea Scrolls).
• The Zealots — political revolutionaries against Roman rule.

Within this religious-political milieu, expectations of a messianic figure who would restore Jewish independence and inaugurate God's kingdom were widespread, though differently conceived.

The historical Jesus

The basic framework

Most scholars (including non-Christian historians) accept the following as historically probable:

• Jesus of Nazareth was born around 4 BCE.
• He was raised in the village of Nazareth in Galilee.
• He was baptised by John the Baptist around 28 CE.
• He conducted a public ministry of teaching and healing for 1-3 years.
• He was crucified under the Roman governor Pontius Pilate in Jerusalem around 30 CE.

The teaching

The Synoptic Gospels (Matthew, Mark, Luke) record Jesus' teaching in the form of:

• Parables — extended metaphorical narratives illustrating the nature of God's kingdom (the Good Samaritan, the Prodigal Son, the Sower, the Mustard Seed).
• Aphorisms — short, memorable sayings, many included in the Sermon on the Mount (Matthew 5-7).
• Beatitudes — blessings on the poor, the meek, the merciful, the peacemakers.

The central themes of Jesus' teaching include:

The crucifixion and resurrection

Jesus was crucified by Roman authority on charges of sedition (claiming to be "King of the Jews"). The crucifixion is dated to either 30 or 33 CE.

The Christian tradition holds that on the third day after his crucifixion, Jesus rose from the dead. The four Gospels record discoveries of an empty tomb and appearances of the resurrected Jesus to his disciples. This event — the Resurrection — is the central claim of Christian faith.

The historical-critical study of the resurrection is contested across confessional and scholarly lines. What is undisputed is that the early Jesus movement understood itself as proclaiming a risen Christ.

The early church and the spread of Christianity

After the resurrection accounts, the Christian movement spread rapidly across the Roman Empire. Key figures and developments:

The apostles

The original twelve apostles led the Jewish-Christian community in Jerusalem, with Peter as the most prominent. Tradition holds that Peter eventually went to Rome and was martyred there.

Paul

Paul of Tarsus (originally Saul), a Jewish Pharisee who became a follower of Jesus after a vision on the road to Damascus, was the most influential figure in spreading Christianity beyond its Jewish base. His missionary journeys took him across Asia Minor and Greece. He authored thirteen of the New Testament's twenty-seven books (or seven, depending on which letters are accepted as authentic by modern scholars).

Paul's theological move was decisive: he argued that Gentiles (non-Jews) could become Christians without first becoming Jews — without circumcision, without observing the dietary laws. This made Christianity a universal religion rather than a Jewish sect.

The growth of the church

By 100 CE, Christian communities existed in cities across the Roman Empire. By 300 CE, Christians may have constituted 5-10% of the empire's population — a significant minority.

The Edict of Milan (313 CE), issued by Emperor Constantine, granted Christians toleration. Constantine's own conversion (whatever its nature) symbolised the alignment of imperial and Christian interests. By 380 CE, under Emperor Theodosius, Christianity became the state religion of the Roman Empire.

The early ecumenical councils

The early church convened a series of ecumenical councils to resolve doctrinal disputes:

Council	Year	Significance
Nicaea I	325	Affirmed Jesus' full divinity against Arianism; Nicene Creed
Constantinople I	381	Completed the Nicene Creed; affirmed the Holy Spirit's divinity
Ephesus	431	Affirmed Mary as Theotokos (God-bearer)
Chalcedon	451	Affirmed Jesus' two natures (divine and human) in one person
Constantinople II	553	Further Christological clarification
Constantinople III	680-81	Affirmed Jesus' two wills (divine and human)
Nicaea II	787	Permitted veneration of icons

These seven councils are accepted as ecumenical by Eastern Orthodox, Roman Catholic, and most Protestant traditions.

The Christian Bible

The Christian Bible has two parts:

The Old Testament

The Old Testament is essentially the Jewish Tanakh, organised differently. Three traditions accept different Old Testament canons:

• Protestant — 39 books, matching the Jewish canon.
• Catholic — 46 books, including 7 additional Deuterocanonical books (Tobit, Judith, Wisdom, Sirach, Baruch, 1 Maccabees, 2 Maccabees).
• Orthodox — additional books beyond the Catholic canon (the precise list varies among Orthodox traditions).

The New Testament

The New Testament consists of 27 books, all written in Greek between approximately 50 and 110 CE. Its structure:

Section	Books
Gospels	Matthew, Mark, Luke, John
History	Acts of the Apostles
Pauline epistles	Romans, 1-2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1-2 Thessalonians, 1-2 Timothy, Titus, Philemon
General epistles	Hebrews, James, 1-2 Peter, 1-2-3 John, Jude
Apocalyptic	Revelation

The four Gospels (the first four books) are the central sources for the life of Jesus.

The New Testament canon was effectively settled by the late 4th century, with the same 27 books recognised across major traditions.

The Trinity

The most distinctive Christian doctrine — and the one that most clearly distinguishes Christianity from Judaism and Islam — is the Trinity: the doctrine that the one God exists in three persons, Father, Son and Holy Spirit.

The doctrine was developed and articulated through the early ecumenical councils. The standard summary is in the Nicene Creed:

We believe in one God, the Father almighty, maker of heaven and earth, of all things visible and invisible. And in one Lord Jesus Christ, the only Son of God, eternally begotten of the Father... begotten, not made, of one substance with the Father... And in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father.

Other central doctrines

Beyond the Trinity, Christian doctrine includes:

The Incarnation

The doctrine that the eternal Son of God became fully human in Jesus Christ — fully divine and fully human, in one person, without confusion or separation. The technical term is hypostatic union.

Original Sin and Redemption

The Christian narrative of salvation:

• The Fall — humanity, through Adam and Eve's disobedience, fell into sin and alienation from God.
• The Atonement — Christ's death on the cross paid the price of human sin.
• Salvation — through faith in Christ's death and resurrection, humans are reconciled to God.

The precise mechanism of atonement has been theologically debated (substitutionary, moral influence, Christus Victor, satisfaction theories).

Eschatology

Christian eschatology includes:

• The Second Coming of Christ.
• The Last Judgement.
• The Resurrection of the dead.
• Heaven (eternal communion with God) and Hell (separation from God).

What CSS questions on this topic typically demand

Three exam shapes:

1. Historical / biographical — "Discuss the life and teaching of Jesus."
2. Doctrinal — "Discuss the doctrine of the Trinity in Christianity."
3. Comparative — "Compare the conceptions of God in Judaism, Christianity and Islam."

A strong answer combines accurate historical knowledge of the early church and councils with clear engagement with the doctrinal content.

What you take from this lesson

Christianity emerged from 1st-century Judaism centred on the life, death and resurrection of Jesus, and was shaped over the next four centuries through Pauline mission, ecumenical councils and imperial recognition. The next lesson examines the major sects of Christianity — Orthodox, Catholic, Protestant — and contemporary Christianity.