Glossary
121 terms in plain English. Underlined words in the chapters link here — hover or tap them for a quick definition.
A
- African Initiated Churches
- Churches founded by Africans independently of missionary control, often stressing prophecy and healing.
See: The Global South
- Aggiornamento
- Italian for "updating": Pope John XXIII's goal for the Second Vatican Council.
- Anabaptist
- "Re-baptizer": radical reformers who baptized only believing adults and formed churches separate from the state.
- Apocalyptic
- Writing that reveals hidden heavenly secrets about the end of the world, through symbolic visions (e.g. Daniel, Revelation).
- Apocrypha
- Books in the Greek Old Testament but not the Hebrew Bible (e.g. Tobit, Maccabees). Catholics and Orthodox count them as Scripture; most Protestants don't.
See: Forming the Bible
- Apologetics
- Reasoned defense of the Christian faith (from Greek apologia, a defense speech).
- Apostolic succession
- The belief that bishops stand in an unbroken line of ordination from the apostles and so guard their teaching.
See: Gnostics, Marcion and the Rise of Orthodoxy, Bishops and Church Order
- Asceticism
- Strict self-discipline (fasting, celibacy, simple living) undertaken for spiritual reasons.
- Assurance
- Confidence, given by the Holy Spirit, that one's sins are forgiven and one is saved.
- Atonement
- How Christ's death reconciles people to God ("at-one-ment").
B
- Baptism
- The rite of washing with water that marks entry into the Christian community, done "in the name of the Father, Son and Holy Spirit."
- Basilica
- A large rectangular Roman hall that Christians adopted as the standard shape for church buildings after Constantine.
See: Constantine
- Believers' baptism
- Baptizing only those old enough to profess faith themselves, rather than infants.
- Bishop
- From Greek episkopos, "overseer": the senior church leader of a city or region, who ordains clergy.
- Book of Common Prayer
- The Church of England's English-language prayer book, first written by Cranmer in 1549.
C
- Canon (of Scripture)
- From Greek for "measuring rod": the official list of books accepted as Scripture.
See: Forming the Bible
- Canon law
- The church's own system of law, governing clergy, sacraments, marriage and church property.
See: Rome and Its Empire
- Cappadocian Fathers
- Basil of Caesarea, Gregory of Nazianzus and Gregory of Nyssa, whose theology clarified the doctrine of the Trinity in the 300s.
- Catechumen
- Someone receiving instruction in preparation for baptism.
- Cenobitic
- Monastic life lived in community under a rule, as opposed to the solitary life of a hermit.
- Charismatic movement
- The spread of Pentecostal-style experience and spiritual gifts into Catholic, Anglican and Protestant churches from the 1960s.
- Christology
- Teaching about who Christ is, especially how he is both divine and human.
- Church of the East
- The ancient church of Persia and Asia, which rejected the Council of Ephesus; once spread to China; often wrongly called "Nestorian."
- Clergy
- People ordained for church ministry (bishops, priests, deacons), as distinct from the laity.
- Cluny
- A great Burgundian abbey (910) that led a network of reformed monasteries and championed splendid liturgy.
See: Monks and Friars
- Conciliarism
- The view that a general council of the church has authority over the pope.
- Confessing Church
- German Protestants who resisted Nazi control of the church, based on the Barmen Declaration (1934).
- Council of Trent
- The Catholic council (1545–1563) that defined doctrine against Protestants and reformed the clergy.
- Covenant
- A binding agreement between God and people, with promises and obligations on both sides.
See: Ancient Israel
- Creed
- From Latin credo, "I believe": a short official summary of Christian belief, e.g. the Apostles' or Nicene Creed.
D
- Deacon
- "Servant": a church officer originally responsible for caring for the poor; later a rank of clergy below priest.
- Dead Sea Scrolls
- Ancient Jewish manuscripts found near Qumran from 1947 onward, including the oldest known copies of biblical books.
- Deism
- Belief in a creator God who does not intervene in the world through miracles or revelation.
See: The Enlightenment
- Denomination
- A distinct organized church body within Christianity (e.g. Methodist, Baptist), especially in the American system.
- Devotio Moderna
- "Modern Devotion": a late medieval movement of simple, inward, disciplined piety among lay people and clergy in the Low Countries.
See: Monks and Friars
- Dhimmi
- "Protected person": a Jew or Christian under Islamic rule, allowed to worship but paying a special tax and facing restrictions.
See: The Challenge of Islam, Orthodoxy in Russia and the Ottoman World
- Diaspora
- "Scattering": Jewish communities living outside the land of Israel.
See: Ancient Israel
- Diocese
- The area under a bishop's care. Originally a Roman administrative district.
See: Rome and Its Empire
- Docetism
- The belief that Christ only "seemed" to have a human body and did not really suffer.
E
- Ecumenism
- The movement to promote unity and cooperation among Christian churches.
- Eucharist
- "Thanksgiving": the sharing of bread and wine in memory of Jesus' Last Supper. Also called Holy Communion, the Lord's Supper or the Mass.
F
- Filioque
- Latin "and the Son": words added in the West to the Nicene Creed, saying the Spirit proceeds from the Father and the Son. Rejected by the Orthodox.
- Friars
- Members of "mendicant" (begging) orders such as Franciscans and Dominicans, who lived in poverty and worked among people rather than in cloisters.
See: Monks and Friars
- Fundamentalism
- A movement (from the 1910s–20s) defending core doctrines and biblical inerrancy against liberal theology.
G
- Glossolalia
- "Speaking in tongues": praying or speaking in a language unknown to the speaker, seen as a gift of the Spirit.
- Gnosticism
- Varied movements (2nd century on) teaching that the material world is evil and salvation comes through secret knowledge (gnosis).
- Grace
- God's free, undeserved favor and help, by which people are forgiven and enabled to love God.
See: Augustine of Hippo
- Great Awakening
- Waves of religious revival in America: the First (1730s–40s) and Second (c. 1795–1840).
H
- Hellenistic
- The Greek-influenced culture of the eastern Mediterranean and Middle East after Alexander the Great (323 BC onward).
See: The Greek Mind
- Heresy
- A teaching the church judged to be a serious departure from the true faith.
- Hesychasm
- An Orthodox tradition of silent inner prayer, especially repeating the Jesus Prayer, seeking union with God.
- Higher criticism
- Historical study of the Bible's authorship, dates, sources and setting, using the methods applied to other ancient texts.
- Holy Spirit
- God's presence and power active in the world and in believers; the third "person" of the Trinity.
- Homoousios
- Greek for "of the same substance." Used at the Council of Nicaea (325) to say the Son is fully God just as the Father is.
- Humanism
- The Renaissance movement to revive classical learning, with the slogan "back to the sources."
I
- Icon
- A sacred image (usually painted on wood) of Christ, Mary or a saint, venerated especially in Orthodox worship.
- Iconoclasm
- "Image-breaking": opposition to and destruction of religious images, as in Byzantium (726–843) and parts of the Reformation.
- Immaculate Conception
- Catholic doctrine (1854) that Mary was conceived free of original sin. (Not the same as the virgin birth.)
- Incarnation
- "Becoming flesh": the belief that God the Son became a real human being in Jesus.
- Inculturation
- Expressing Christian faith through the language, customs and thought of a particular culture.
- Indulgence
- A grant by the church reducing the punishment still due for forgiven sins, often in purgatory; later sold for money.
See: The Crusades, The Late Medieval Crisis, Christianity on the Eve of Reform
- Inner Light
- The Quaker belief that Christ's light is present in every person and can guide them directly.
- Inquisition
- Church tribunals set up (from the 1230s) to investigate and punish heresy; the later Spanish and Roman Inquisitions were separate institutions.
See: Monks and Friars
- Interdict
- A church penalty suspending sacraments and services in a whole area, to pressure its ruler.
See: Popes Against Kings
- Investiture
- The ceremony of installing a bishop with ring and staff; the fight over who had the right to do it.
See: Popes Against Kings
J
- Jesuits
- The Society of Jesus, founded by Ignatius of Loyola in 1540, known for education and missions.
- Justification
- Being made or declared right with God. Luther taught it comes by faith alone; the Catholic Church taught faith working through love.
See: Martin Luther
L
- Liberal theology
- A 19th–20th century Protestant movement restating Christianity in terms of modern thought, experience and ethics.
- Liberation theology
- Latin American theology (from c. 1968) reading the Bible from the side of the poor and seeking justice.
See: The Global South
- Logos
- Greek for "word" or "reason." Philosophers used it for the rational order of the universe; John's Gospel uses it for Christ.
See: The Greek Mind, Writing the New Testament, Apologists and Thinkers
M
- Martyr
- Greek for "witness": someone killed because of their faith.
- Messiah
- Hebrew for "anointed one" (Greek: Christos). A king God would send to rescue Israel. Christians believe Jesus is the Messiah.
- Miaphysite
- Belief that in Christ divinity and humanity are united in "one nature." Held by the Oriental Orthodox churches, who rejected Chalcedon.
See: Who Is Christ? Ephesus and Chalcedon, Churches Beyond Chalcedon
- Millet
- A religious community in the Ottoman Empire, governed through its own religious leaders.
- Monasticism
- A way of life withdrawn from ordinary society for prayer and self-discipline, alone (hermits) or in communities (monks, nuns).
- Monotheism
- Belief that there is only one God.
See: Ancient Israel
- Mysticism
- The pursuit of direct, inward experience of and union with God.
See: Monks and Friars
N
- Neo-orthodoxy
- Karl Barth's 20th-century theology that rejected liberalism and stressed God's self-revelation in Christ and Scripture.
- Neoplatonism
- A late form of Plato's philosophy (from c. AD 250) teaching that everything flows from a perfect "One" and the soul longs to return to it.
See: The Greek Mind, Apologists and Thinkers, Augustine of Hippo
- Nicene Creed
- The creed of Nicaea (325) as expanded at Constantinople (381); the most widely shared Christian statement of faith.
See: Arius and the Council of Nicaea, The Great Schism of 1054
O
- Old Believers
- Russian Orthodox Christians who rejected Patriarch Nikon's liturgical reforms in the 1650s–60s.
- Ordination
- The rite (laying on of hands and prayer) by which someone is made a deacon, priest or bishop.
- Original sin
- The teaching, developed by Augustine, that Adam's fall damaged all humanity, so everyone is born inclined to sin.
See: Augustine of Hippo
- Orthodoxy
- "Right belief": the teaching accepted by the mainstream church. (Capitalized, also the Eastern Orthodox churches.)
P
- Papacy
- The office of the pope, the bishop of Rome, whom Catholics regard as the successor of Peter and head of the church on earth.
See: Rome and Its Empire, The Church in Jerusalem, Bishops and Church Order
- Papal infallibility
- Catholic doctrine (1870) that the pope cannot err when formally defining faith or morals for the whole church.
- Papal States
- Territories in central Italy ruled by the popes as temporal princes from 756 to 1870.
- Pax Romana
- "The Roman peace": roughly 27 BC – AD 180, when the empire was relatively stable and safe for travel and trade.
See: Rome and Its Empire
- Penance
- Acts of sorrow and repair for sin, and the church's process for forgiving and restoring sinners; later a sacrament (confession).
- Pentecost
- A Jewish harvest feast fifty days after Passover; for Christians, the day the Holy Spirit came on the disciples.
- Pentecostalism
- A movement (from 1906) emphasizing baptism in the Holy Spirit, speaking in tongues, healing and lively worship.
- Pharisees
- A popular Jewish movement devoted to applying God's law to daily life; ancestors of rabbinic Judaism.
- Pietism
- A Lutheran renewal movement (from 1675) stressing personal conversion, Bible study, holy living and active love.
- Predestination
- The belief that God has chosen in advance who will be saved.
- Presbyter
- "Elder": a church leader; the word from which "priest" comes.
See: Bishops and Church Order, Zwingli, Calvin and the Reformed
- Priesthood of all believers
- Luther's teaching that all baptized Christians have direct access to God and share in Christ's priesthood.
- Purgatory
- In Catholic teaching, a state of cleansing after death for saved souls not yet ready for heaven.
See: Gregory the Great and the Conversion of Europe, Christianity on the Eve of Reform
R
- Reformed
- The Protestant tradition from Zwingli and Calvin (Presbyterian, Dutch Reformed, Congregational), distinct from Lutheran.
- Relic
- A physical remain of a saint (bones, clothing) or an object linked to Christ or the saints, venerated by believers.
- Resurrection
- Being raised bodily from death to new life. Christians believe Jesus rose and that all will be raised at the end.
S
- Sacrament
- A sacred rite seen as a visible sign of God's grace. Catholics and Orthodox count seven; most Protestants two (baptism and the Lord's Supper).
- Scholasticism
- The method of medieval universities: using logic and debate to understand and systematize Christian faith.
- Secularism / secularization
- Secularism: keeping religion separate from government and public life. Secularization: the decline of religion's influence in society.
See: Revolution and the Church, Christianity Today and Tomorrow
- Septuagint
- The Greek translation of the Hebrew Scriptures made in Alexandria from about 250 BC; the Bible of the earliest Christians.
See: The Greek Mind, Judaism in the Time of Jesus, Writing the New Testament, Forming the Bible
- Simony
- Buying or selling church offices or spiritual things.
See: Popes Against Kings
- An early 20th-century movement teaching that Christianity must reform unjust social structures.
- Sola scriptura
- "Scripture alone": the Protestant principle that the Bible is the supreme authority over church tradition.
See: Forming the Bible
- Stoicism
- A Greek philosophy teaching that a divine reason orders the world and that the wise accept fate with calm self-control.
See: The Greek Mind
- Symphonia
- The Byzantine ideal of harmony between emperor and church, each with its own role under God.
- Synagogue
- "Gathering": a Jewish house of prayer, Scripture reading and teaching.
- Synoptic Gospels
- Matthew, Mark and Luke, which share much material and can be "seen together" side by side.
- Syriac
- A dialect of Aramaic used by many Middle Eastern Christians; a major language of early Christian literature.
T
- Theosis
- "Deification": the Orthodox teaching that salvation means sharing in God's own life by grace.
- Theotokos
- Greek for "God-bearer" or "Mother of God": a title for Mary affirmed at the Council of Ephesus (431).
- Toleration
- Allowing people to practice a religion one disapproves of, without punishment.
See: Reformation Legacies
- Transubstantiation
- Catholic teaching that in the Mass the bread and wine truly become Christ's body and blood in their inner reality ("substance") while still looking like bread and wine.
See: The Greek Mind, Popes Against Kings, The Late Medieval Crisis
- Trinity
- The Christian belief that the one God exists as three "persons": Father, Son and Holy Spirit.
U
- Ultramontanism
- The 19th-century movement favoring a strong, centralized papacy ("beyond the mountains" = Rome).
V
- Vocation
- "Calling": the Reformation idea that ordinary work and family life can be a holy calling from God.
See: Reformation Legacies
- Vulgate
- Jerome's Latin translation of the Bible (c. 382–405), the standard Bible of Western Christianity for a thousand years.
See: Forming the Bible
Z
- Zoroastrianism
- The ancient religion of Persia, teaching a struggle between a good god (Ahura Mazda) and evil.