Reference · Terms in Plain English
The Glossary
Theology has its own vocabulary, and a lot of heat comes from words people use without quite defining. What is the difference between heresy and heterodoxy? Between a schism and a heresy? What exactly is a dogma, a canon, a straw man? This is the plain-English dictionary — each term defined clearly, with the distinctions that actually matter. For the original Greek and Hebrew words, see the Lexicon.
Orthodoxy & Error
How the Church classifies belief and division — what counts as heresy, heterodoxy, schism, or an open question.
Adiaphora
“Things indifferent” — matters neither commanded nor forbidden, on which Christians may freely differ without breaking fellowship.
Anathema
A formal curse or condemnation pronounced by a council on a heresy or its teachers — “let it be accursed.”
Apostasy
The abandonment of the faith altogether — a falling away from Christianity, not merely an error within it.
Doctrine
A teaching of the Church — what Scripture is understood to teach on a subject. Broader than dogma; ranges from essential to debatable.
Dogma
A doctrine formally defined and held as binding and beyond dispute — the settled, non-negotiable core of the faith.
Heresy
A belief that contradicts a core, defined doctrine of the Christian faith — not mere error, but denial of something essential.
Heretic
A person who holds and promotes a heresy — historically, one who obstinately denies a defined doctrine after correction.
Heterodoxy
“Other belief” — teaching that departs from orthodoxy but stops short of outright heresy; off-center rather than over the line.
Orthodoxy
Right belief — teaching that matches the historic Christian faith as defined by Scripture and the ecumenical creeds.
Orthopraxy
“Right practice” — living rightly: worship, ethics, and obedience, as the counterpart to orthodoxy's right belief.
Schism
A formal split in the Church's communion — a break in unity over authority, practice, or jurisdiction, rather than over a core doctrine.
Key Doctrines
The great teachings themselves — incarnation, atonement, justification, the sacraments, predestination, the last things.
Assurance (of Salvation)
The believer's settled confidence of being in a state of grace — grounded in Christ's work, the Spirit's witness, and the fruit of a changed life.
Atonement
How the death of Christ reconciles sinners to God — “at-one-ment,” the restoration of a broken relationship. The fact is universal; the theories explain the mechanism.
Common Grace
God's non-saving goodness shown to all people — sun and rain, conscience, beauty, civic order — restraining evil and sustaining the world.
Efficacious Grace
Grace that infallibly accomplishes its purpose in the one it is given to — closely related to irresistible grace and effectual calling.
Election
God's choosing of a people for himself — Israel in the Old Testament, the Church in the New (Eph 1:4). The ground of that choice is the debated point.
Eternal Security
The belief that a genuinely saved person can never be lost — popularly 'once saved, always saved.'
Glorification
The final stage of salvation — the believer's complete conformity to Christ at the resurrection, freed from sin and given a glorified body.
Imputation
To credit or reckon to someone's account — sin reckoned to Christ, and his righteousness reckoned to the believer (2 Cor 5:21).
Incarnation
The doctrine that the eternal Son of God took on human nature — “the Word became flesh” (John 1:14) — being fully God and fully man in one person.
Irresistible Grace
The Reformed teaching (the 'I' of TULIP) that God's saving grace effectually draws the elect so that they certainly come to faith — also called effectual calling.
Justification
God's act of declaring a sinner righteous in his sight — the central word of the Reformation debate, defined differently across traditions.
Means of Grace
The ordinary channels through which God conveys or strengthens grace — classically the Word, the sacraments, and prayer.
Monergism
The view that regeneration is the work of God alone — one worker — the sinner being passive in the new birth.
Ordo Salutis
'The order of salvation' — the logical sequence of God's saving acts: calling, regeneration, faith, justification, sanctification, glorification.
Original Sin
The doctrine that, through Adam's fall, sin and its corruption pass to the whole human race — we are born inclined to sin, not morally neutral.
Perseverance of the Saints
The Reformed teaching (the 'P' of TULIP) that those truly regenerated by God will persevere in faith to the end and cannot finally fall away.
Predestination
God's eternal purpose concerning the salvation of his people — that he foreordains; how it relates to human freedom is the long debate.
Prevenient Grace
Grace that 'goes before' — God's enabling work that precedes and makes possible any human turning to him.
Propitiation
The turning away of righteous wrath by a sacrifice — Christ's death satisfying God's just judgment against sin (Rom 3:25; 1 John 2:2).
Providence
God's continual upholding and governing of all creation and history — sustaining, directing, and working all things toward his purposes.
Real Presence
The belief that Christ is truly present in the Lord's Supper — affirmed across most traditions, but explained very differently.
Regeneration
The new birth — God's act of giving spiritual life to the dead, making a person a new creation (John 3:3; Titus 3:5).
Sacrament
A sacred sign instituted by Christ that conveys or signifies grace — classically baptism and the Lord's Supper; more in Catholic and Orthodox count.
Sanctification
Being made holy — the lifelong work of growing into Christlikeness after (or, in some traditions, as part of) justification.
Synergism
The view that salvation involves a real cooperation between God's grace and the human will's free response.
Total Depravity
The Reformed teaching that sin corrupts every part of a person (mind, will, affections) — not that people are as bad as possible, but that no part is left untouched.
Authority & Sources
Where teaching comes from and what binds — Scripture, canon, creed, council, tradition, dogma.
Apocrypha
“Hidden” writings outside a given canon — the term Protestants use for the deuterocanon, and the word for non-canonical works generally.
Canon
The official list of books recognized as Scripture — the measuring rule of what counts as the Bible.
Confession (of faith)
A detailed doctrinal statement adopted by a church or tradition — longer and more specific than a creed.
Creed
A short, authoritative summary of the faith, confessed corporately — from Latin credo, “I believe.”
Deuterocanon
“Second canon” — books (Tobit, Sirach, 1–2 Maccabees, etc.) in Catholic and Orthodox Bibles that Protestants place outside the canon.
Ecumenical Council
A churchwide assembly of bishops convened to settle doctrine and order for the whole Church — e.g. Nicaea (325), Chalcedon (451).
Inerrancy
The claim that Scripture, in its original manuscripts, tells the truth and does not err in all that it affirms.
Infallibility
The quality of not failing or misleading — used of Scripture (it will not deceive in faith and practice) and, in Catholicism, of the Church's defined teaching under set conditions.
Inspiration (of Scripture)
The doctrine that God so superintended the human authors of Scripture that their writings are his word — “God-breathed” (2 Tim 3:16).
Magisterium
The official teaching authority of the Roman Catholic Church (the pope and bishops in communion with him). A Catholic concept.
Rule of Faith
The early Church's summary of core apostolic teaching, used as the lens for reading Scripture rightly before the creeds were formalized.
Sacred Tradition
The faith handed down from the apostles through the Church's teaching, worship, and life — alongside or under Scripture, depending on the tradition.
Study & Method
How to read and reason about the text — exegesis, hermeneutics, apologetics, and their pitfalls.
Apologetics
The reasoned defense of the Christian faith — giving “a reason for the hope that is in you” (1 Peter 3:15).
Biblical Theology
Tracing how a theme unfolds across the Bible's storyline — following revelation as it develops from Genesis to Revelation.
Eisegesis
Reading one's own ideas INTO a text — the error of making a passage say what you already wanted it to say.
Exegesis
Drawing the meaning OUT of a text — careful interpretation that lets the passage say what its author meant.
Hermeneutics
The principles and method of interpretation — the “rules of the road” for reading a text rightly.
Proof-texting
Quoting an isolated verse out of its context to “prove” a point the verse may not actually support.
Systematic Theology
Organizing the Bible's teaching by topic — what all of Scripture says about God, sin, salvation, the Church, the last things.
Theology
“Words about God” — the disciplined study of God and of all things in relation to God.
Typology
Reading earlier persons, events, and institutions as God-intended patterns (“types”) that foreshadow Christ and the gospel.
Reasoning & Fallacies
The moves arguments make, fair and foul — claims, evidence, and the common fallacies named plainly.
Ad Hominem
Attacking the person making an argument instead of the argument itself — “to the man,” not to the point.
Appeal to Authority
Treating a claim as proven just because an authority asserts it — fallacious when the authority is irrelevant, biased, or not actually expert.
Argument from Silence
Inferring a conclusion from the ABSENCE of evidence — “the text doesn't mention it, so it didn't happen / isn't true.”
Begging the Question
Assuming the very thing you're trying to prove — the conclusion is smuggled into the premises.
Burden of Proof
The responsibility to support a claim — it rests on the one asserting it, not on others to disprove it.
Equivocation
Using one word in two different senses within an argument, so a conclusion only seems to follow.
Fallacy
A flaw in reasoning that makes an argument invalid or misleading, even when it sounds persuasive.
False Dichotomy
Presenting only two options as if they were the only ones, when other possibilities exist.
Genetic Fallacy
Judging a claim true or false based on its ORIGIN rather than its merits — where it came from, not whether it's sound.
Hearsay
Secondhand report offered as if it were firsthand evidence — “someone said that someone said,” without the original source.
Non Sequitur
“It does not follow” — a conclusion that isn't actually supported by the premises that came before it.
Straw Man Fallacy
Misrepresenting someone's argument in a weaker form, then refuting the weak version instead of what they actually said.
Movements & -isms
The major -isms and positions, defined neutrally so you can recognize them when you meet them.
Amillennialism
The view that the “thousand years” of Revelation 20 is symbolic of the present church age — Christ reigns now, and returns to the final judgment and new creation.
Arianism
The 4th-century teaching of Arius that the Son is a created being — godlike but not God. Condemned at Nicaea (325).
Arminianism
The tradition stemming from Jacob Arminius, holding that grace is resistible and election is conditioned on foreseen faith — God enables a genuine free response.
Calvinism
The Reformed theological tradition stemming from John Calvin, stressing God's sovereignty in salvation — popularly summarized by the five points (TULIP).
Christus Victor
The view that on the cross Christ defeated sin, death, and the devil — atonement as cosmic victory and liberation.
Covenant Theology
A framework that reads the whole Bible through a series of divine covenants — classically the covenants of redemption, works, and grace — stressing the unity of God's one people.
Dispensationalism
A framework dividing redemptive history into distinct eras (dispensations) and maintaining a sharp distinction between Israel and the Church — associated with premillennial, often pretribulational, eschatology.
Docetism
The early error that Christ only SEEMED to have a body and to suffer — denying the reality of the incarnation.
Gnosticism
A diverse early movement teaching salvation through secret knowledge (gnosis), often despising the material world and the body.
Memorialism
The view (associated with Zwingli and much of the free-church tradition) that the Lord's Supper is chiefly a memorial — “do this in remembrance of me” — without a change in the elements.
Modalism
The error that Father, Son, and Spirit are not three distinct persons but one person in three successive “modes” or masks.
Nestorianism
The teaching (associated with Nestorius) that divides Christ too sharply — as if into two persons rather than one person in two natures.
New Covenant Theology
A middle framework holding that the New Covenant fulfills and transforms the Old — Christ, not the Mosaic law, is the direct rule of life — without dispensationalism's Israel/Church split.
Pelagianism
The teaching of Pelagius that humans can take the first steps toward salvation by their own free will, without the necessity of grace. Condemned in the 5th century.
Penal Substitution
The view that Christ bore the penalty for sin in the sinner's place — taking the judgment we deserved so we could be acquitted.
Premillennialism
The view that Christ returns BEFORE a literal thousand-year reign (the millennium) on earth (Rev 20).
Ransom Theory
The early-church image of Christ's death as a ransom that frees humanity from bondage to sin, death, and the devil (Mark 10:45).
Satisfaction Theory
Anselm's view that sin dishonors God's majesty, and Christ's death renders the satisfaction owed — restoring the moral order.
Sola Fide
'Faith alone' — the sinner is justified (declared righteous) through faith alone, apart from works of the law.
Sola Gratia
'Grace alone' — salvation is wholly a gift of God's unmerited favor, not earned by human works or merit.
The Five Solas
The five Latin 'alone' slogans summarizing Reformation theology: Scripture alone, grace alone, faith alone, Christ alone, to the glory of God alone.
Transubstantiation
The Catholic doctrine that at consecration the substance of the bread and wine becomes the body and blood of Christ, while the appearances remain.