Early Christian Church: Key Figures, Councils, and Doctrines

Early Church

The first centuries of Christianity when the faith spread despite persecution and councils shaped beliefs.

Apostolic Age

Period when the Apostles spread Jesus' teachings guided by the Great Commission.

Great Commission

Jesus' command to the Apostles to go and make disciples of all nations.

Saul / Paul

A persecutor who converted after encountering Christ; became the Church's greatest missionary.

Stephen

The first Christian martyr; his dying words mirrored Christ's forgiveness on the Cross.

Peter

Leader of the Apostles and head of the early Church in Rome; recognized as the first Pope.

Universality

Paul's teaching that salvation through Christ is open to all people, not just Jews.

Communal Living

Apostles lived together and shared possessions, reflecting unity and charity.

First Pope

Peter, as head of the Church in Rome, seen as the first visible leader of the Church.

Council of Jerusalem

First Church council deciding Gentiles didn't need to follow Jewish law for salvation.

Martyrdom

Dying for one's faith; inspired others and increased interest in Christianity.

Persecution

Christianity was illegal for 300 years, seen as a threat to Jewish and Roman power.

Council of Nicaea

First major council (325 AD) that affirmed Jesus is of the same essence as the Father (homoousias).

Nicene Creed

Statement of belief created at Nicaea summarizing core Christian truths and faith in the Trinity.

Spread of Christianity

Aided by Roman roads, Pax Romana, common language, and message of love and mercy.

Role of Rome

Spiritual and geographic center where Peter and Paul were martyred; disputes resolved by the Bishop of Rome.

Development of the Papacy

The Bishop of Rome became the Pope, visible head of the Church by the 4th-5th centuries.

Ecclesiology

Study of the nature and structure of the Church and its identity.

Four Marks of the Church

One, Holy, Catholic, and Apostolic — the essential traits of the true Church.

One

The Church is united in faith under one God.

Holy

The Church is real though imperfect and set apart for God.

catholic

Means 'universal'; the Church is for all people and fully contains God's truth.

Apostolic

Founded on the Apostles and continues their mission.

Apostles' Creed

Early, brief statement of Christian belief used by the early Church.

Nature of Christ

Jesus is both fully human and fully divine — same essence as the Father.

Holy Spirit

Third Person of the Trinity; unites and guides the Church.

Trinity

One God in three Persons — Father, Son, and Holy Spirit.

Body of Christ

Image of the Church as one body with Christ as the head.

Household of God

Image of the Church as a family with God as Father and believers as children.

Bride of Christ

The Church is loved by Christ as a bride is loved by her groom.

Christendom

Period when Church and society were united under Christianity.

Medieval Church

The Church became a stabilizing force after Rome's fall.

Fall of Roman Empire

Collapse in 476 AD caused by corruption, instability, and invasions.

Iconoclast

Person who opposed the use of religious images or icons.

Iconodules

Person who is for the use of religious images or icons.

Eastern Church

Greek-speaking Church centered in Constantinople.

Western Church

Latin-speaking Church centered in Rome.

Priest

Ordained minister serving the Church community and celebrating the sacraments.

Patriarch

High-ranking bishop in the Eastern Church.

Great Schism (1054 AD)

Official split between Eastern Orthodox and Roman Catholic Churches.

Monasticism

Way of life where monks and nuns withdraw from the world for prayer and community living.

Ecclesiastical Authority

The Church's power to lead, teach, and govern believers.

Prayer Types

Liturgy of the Hours (daily prayer), Lectio Divina (Scripture meditation), and Ora et Labora ("pray and work").

Reformation

Movement protesting corruption in the Church; led to new Christian denominations.

Simony

Buying or selling Church positions.

Indulgences

Promises of reduced punishment for sin; often abused before reform.

Nepotism

Giving Church offices to family members.

Absenteeism

Bishops not visiting or caring for their dioceses.

Pluralism

One bishop overseeing multiple dioceses.

Council of Trent (1545-1563)

Reaffirmed Catholic teachings, improved priest education, and emphasized both Scripture and Tradition.

Catholic Counter-Reformation

Movement to renew the Church and respond to Protestant challenges.

Jesuits

Religious order founded by St. Ignatius of Loyola; focused on education, missions, and defending the faith.

Vatican I (1869-1870)

Declared Papal Infallibility; council ended early due to war.

Papal Infallibility

Pope is protected from error when formally teaching on faith and morals.

Vatican II (1962-1965)

Council called by Pope John XXIII to renew the Church; promoted engagement with the modern world.

Aggiornamento

"Bringing up to date" — renewing the Church while staying rooted in tradition.

Semper Reformanda

"Always reforming" — continual renewal and conversion of the Church.

Liturgical Reform

Mass celebrated in local languages with full participation of the faithful.

Interfaith Dialogue

Promoting understanding between the Catholic Church and other religions.

Ecumenism

Movement to restore unity among all Christian churches.

Modern Papacy

The Pope serves as global leader promoting peace, justice, and care for the poor.

St. John Paul II (1978-2005)

Focused on global outreach and interfaith dialogue; stood against communism and promoted human dignity.

Pope Benedict XVI (2005-2013)

Theologian and teacher who emphasized tradition and harmony between faith and reason.

Pope Francis (2013-2025)

First pope from the Americas; focuses on mercy, humility, and care for the poor and planet; wrote Laudato Si' and Fratelli Tutti.