Christian Theology

Introduction

Christian theology is the 2,000-year intellectual project of making sense of what Christians believe — not as a set of pious assertions, but as a rigorous body of thought that has, more than any other tradition, shaped the metaphysical assumptions of Western civilization. To understand the Western world's debates about being, time, freedom, evil, and personhood, you need to understand the theology those debates emerged from, even if you are not a believer.

Founding moment

Christian theology emerges from the first-century Christian movement's need to articulate what it was, against the background of Hellenistic Judaism and Greek philosophy. The New Testament writings, especially the letters of Paul and the Gospel of John, perform the first major theological work: identifying Jesus with the divine Logos of Greek thought, articulating salvation as participation in his death and resurrection, and reframing Jewish covenant theology around the inclusion of Gentiles.

The systematic phase begins with the Apostolic Fathers (Clement of Rome, Ignatius) in the late first and early second century, and accelerates with the Apologists (Justin Martyr, Athenagoras) who defended Christianity to Greco-Roman audiences using Greek philosophical vocabulary. By the third century, Origen of Alexandria is producing systematic theology of remarkable scope. The first ecumenical councils — Nicaea (325), Constantinople (381), Ephesus (431), Chalcedon (451) — settle (and create) the central trinitarian and christological debates that define orthodox Christianity.

Core doctrines

The creeds of the first four councils define what is shared across most of orthodox Christianity:

1. The Trinity. God is one essence (ousia) in three persons (hypostases): Father, Son, and Holy Spirit. The persons are distinct but share the single divine essence. This is the most distinctive Christian metaphysical claim and the one that required the most sophisticated philosophical work to articulate.
2. The Incarnation. The Son of God became human in Jesus Christ. The Council of Chalcedon (451) defined Christ as one person in two natures (divine and human), fully God and fully man, without confusion, change, division, or separation.
3. Creation from nothing. The world is created ex nihilo by God. It is not eternal, not necessary, not a divine emanation. This is a sharp break from both Aristotelian (eternal cosmos) and Neoplatonic (emanationist) metaphysics.
4. Fall and redemption. Human beings are created good but have fallen through sin; redemption comes through Christ's incarnation, death, and resurrection.
5. Resurrection of the body. Not the immortality of the soul (which Christianity inherits from Platonism with mixed feelings), but the bodily resurrection of the dead at the end of time.
6. The Church. A visible, sacramental community continuous with the apostles, through which salvation is mediated.

Denominational traditions add further distinctive doctrines (papal authority for Catholicism, sola scriptura and sola fide for the Reformation, the theology of the icon for Eastern Orthodoxy).

Major figures

Far too many to list comprehensively. The pivot points:

• Paul (~5 – ~65 CE) — the New Testament's first systematic theologian.
• Origen of Alexandria (~185 – ~253) — the first great systematic theologian.
• Augustine of Hippo (354 – 430) — the most influential theologian of the Latin West.
• Pseudo-Dionysius (late 5th C) — the most influential mystical theologian.
• John of Damascus (~675 – 749) — systematized Eastern theology.
• Anselm of Canterbury (1033 – 1109) — ontological argument; Cur Deus Homo.
• Thomas Aquinas (1225 – 1274) — Summa Theologiae; the supreme Scholastic theologian.
• Bonaventure (1221 – 1274) — the great Franciscan alternative.
• Martin Luther (1483 – 1546) — the Reformation; Bondage of the Will.
• John Calvin (1509 – 1564) — Institutes of the Christian Religion.
• Friedrich Schleiermacher (1768 – 1834) — the father of liberal theology.
• Karl Barth (1886 – 1968) — Church Dogmatics; the most important Protestant theologian of the 20th century.
• Hans Urs von Balthasar (1905 – 1988) — the great Catholic theologian of beauty.
• John Zizioulas (1931 – 2023) — Eastern Orthodox; Being as Communion.

Major texts

• Augustine, Confessions; City of God; On the Trinity
• Aquinas, Summa Theologiae; Summa Contra Gentiles
• Anselm, Proslogion; Cur Deus Homo
• Luther, On the Bondage of the Will
• Calvin, Institutes of the Christian Religion
• Schleiermacher, The Christian Faith
• Barth, Church Dogmatics

Internal tensions and rival schools

Christian theology is, internally, a long series of fights about how to hold together its various commitments. The deepest splits:

• East / West: the Great Schism of 1054, with roots going back centuries, separated Catholic and Orthodox traditions. The technical issues (the filioque clause in the Nicene Creed, papal primacy) reflected deeper differences in theological method and sensibility.
• Catholic / Protestant: the 16th-century Reformation, splitting over the authority of Scripture vs. tradition, the role of works in justification, the nature of the sacraments, and the structure of the Church.
• Liberal / orthodox: the modern split, with liberal theology (post-Schleiermacher) attempting to reconcile Christianity with modern criticism, science, and historical consciousness, and orthodox traditions resisting.
• Faith and reason: a recurring question about whether and how reason can supplement, support, or critique revelation. Aquinas's confidence in reason, Luther's suspicion of it, Barth's near-rejection of it as a path to God — each represents a major answer.

The external rivals included Greco-Roman paganism, Gnosticism, Judaism, Islam (especially in the medieval period), modern atheism, and the emerging natural sciences. Each rivalry produced significant theological development.

Legacy

Christian theology has shaped Western thought to an extent that is easy to underestimate. Most of the metaphysical categories of medieval and early modern philosophy were developed in theological contexts: substance, essence, person, freedom, will, providence. The modern concept of the individual is theologically inflected. Political concepts like rights and equality emerged in part from theological commitments.

The ongoing influence is most visible in:

• Continental philosophy: Kierkegaard, Hegel, Heidegger, Levinas, Derrida, Marion, and many others worked in explicit conversation with theological themes.
• Anglophone philosophy of religion: a thriving subfield in the analytic tradition with figures like Alvin Plantinga, Eleonore Stump, Richard Swinburne.
• Modern ethics: even secular ethics retains much that emerged from Christian moral theology, often without recognizing the source.
• Western literature and art: the imaginative vocabulary remains substantially theological, even in self-consciously secular work.

The contemporary academic study of Christian theology spans Catholic, Orthodox, mainline Protestant, evangelical, and post-secular settings, with substantial recent work in analytic theology (Oliver Crisp, William Wood), post-liberal theology (the Yale school of Hans Frei and George Lindbeck), political theology (Stanley Hauerwas, Rowan Williams), and theological retrieval of patristic and medieval sources. The discipline maintains close engagement with biblical studies, philosophy of religion, and the history of doctrine.

The most consequential intellectual tradition in Western history, whether or not you are a believer.