We believe in one God

The Text

The opening of the great conciliar creed of the undivided Church. Two words bear the load: we and one. The first names the confessing subject — not the isolated believer but the whole catholic Church speaking through her gathered bishops. The second names the confessed object — one God, not the gods the Greco-Roman world worshiped, not the two gods the Marcionites posited, not the demiurge the Gnostics distinguished from the high God of the philosophers. One. The same word the Shema speaks (Hear, O Israel, the Lord our God, the Lord is one — Deut. 6:4); the same word Paul places at the center of the Christian confession (for us there is one God, the Father, from whom are all things and for whom we exist — 1 Cor. 8:6). The creed of Nicaea begins by re-affirming the most ancient confession Israel ever made, and by speaking it in the voice of a Church that has now grown to include the nations.

Translation Notes

Pisteúomen / credo — we believe / I believe. The Greek conciliar text uses the plural (pisteúomen) — we believe. The Latin liturgical translation shifted to the singular (credo) — I believe — for use in the Western baptismal and eucharistic liturgy, where the creed is prayed by the individual. The two registers are not in conflict; they name different liturgical settings and different aspects of the same confession. We believe is the council’s voice, the Church’s voice, the voice of the gathered baptized community. I believe is the same confession, made personal: the individual believer’s incorporation by faith into the we the creed names. The 20th-century ecumenical translations (ICET 1975, ELLC 1988, BCP 1979 Rite II) returned to the plural to recover the conciliar dimension and to acknowledge that the Nicene Creed is the eucharistic confession of the assembled Church, not a private baptismal interrogation. The 2011 Roman Missal moved Catholic English use back to the singular, on the grounds that the Latin original is what is being translated. The Methodist tradition has preferred the plural since at least the 1989 United Methodist Hymnal. Either form is theologically defensible; the pastoral teacher should know that the shift occurred, and why, and what it accents.

Eis hena Theon / in unum Deum — in one God. The Greek and Latin both use the strong preposition (Greek eis, Latin in + accusative) that denotes movement-into rather than merely opinion-about. To believe in God, in the creed’s idiom, is to entrust oneself into God — to give one’s life into God’s hands, not merely to grant intellectual assent to a proposition about God’s existence. The patristic distinction between credere Deum (to believe that God is), credere Deo (to believe God, i.e. to credit his word), and credere in Deum (to believe into God, i.e. to entrust oneself to him) is older than the creed and is the framework against which the creedal credo in should be read. Faith is not the holding of an opinion; faith is the entrustment of a life.

Hena / unum — one. The numerical adjective is emphatic and is the defining theological claim of the clause. In the 4th-century Greco-Roman world, the affirmation of one God was the contested confession. The pagan pantheon, the philosophical multiple ultimates, the Gnostic and Marcionite postulation of distinct deities for creation and redemption — these were the live alternatives. The creed’s one is not a metaphysical generality (there is one ultimate principle, however conceived); it is the determinate confession of the one God of Israel, now confessed by the church of the nations, who is Father, Son, and Holy Spirit. The doctrine of the Trinity is, in the creedal grammar, a doctrine of the one God — not a softening of monotheism toward tri-theism, but a deepening of the confession of the one God’s life as eternal communion. The phrases that follow in articles 2 and 3 unfold what the one of article 1 already contains.

Historical Context

The Nicene confession of one God must be read against three historical horizons.

The Old Testament Shema. The deepest substrate is Deuteronomy 6:4: Hear, O Israel: the Lord our God, the Lord is one (Shema Yisra’el, Adonai Eloheinu, Adonai echad). The daily prayer of observant Jews from the second-temple period to the present, the Shema is the foundational confession of Israel’s relation to her God. The early church received it without modification: one God, the Father, from whom are all things (1 Cor. 8:6); there is one God, and there is one mediator between God and humanity, the human being Christ Jesus (1 Tim. 2:5); you believe that God is one; you do well — even the demons believe and shudder (James 2:19). The Christian confession of the one God is, before it is anything else, the Christian appropriation of Israel’s Shema.

The Greco-Roman polytheistic context. The 4th-century church confessed her one God in a Mediterranean world saturated with the gods — Zeus and Hera and Apollo and Artemis and the household lares and the city’s genius and the emperor’s cult. The Christian refusal to worship the gods was the immediate cause of the persecutions; the Roman name for Christians, in the second-century imperial registers, was atheists — those who deny the gods. The Nicene confession of one God is the church’s continuation of that confession. Hena Theon — one God — is the line over which the early martyrs went.

The fourth-century intra-Christian debates. The proximate context of the Nicene Creed is the Arian controversy — the question of whether the Son is of the same being with the Father (the Nicene confession, articulated in clause 8 of this corpus, of one Being with the Father) or a created intermediary distinct in being from the Father. The Arian alternative would have produced, on its own logic, two gods (a high uncreated God and a lower created divine being who served as the Father’s instrument). The Nicene confession of one God in article 1, taken together with the confession of one Lord Jesus Christ… of one Being with the Father in article 2, refuses that alternative. The one God of Nicaea is the Father, Son, and Holy Spirit confessed in the unity of one divine being. The doctrine of the Trinity is, on the Nicene grammar, the doctrine of the Christian monotheism.

The Council of Constantinople in 381 expanded the third article on the Holy Spirit (under the influence of the Cappadocian theologians, especially Basil of Caesarea’s On the Holy Spirit and Gregory of Nazianzus’s Theological Orations) and produced what is now standardly called the Nicene-Constantinopolitan Creed (or, simply, the Nicene Creed). The Western Latin tradition adopted the creed in the 6th–8th centuries, and the filioque — and the Son — was added to clause 17 in Spain and Frankish regions before being received in Rome by the early 11th century. The filioque will be discussed in its own annotation; for article 1, the relevant point is that the one God confession of the Nicene Creed is the shared confession of all branches of Christianity, undivided by the later controversies.

Lines of Interpretation

Patristic

Tradition: Irenaeus, Against Heresies I–II (on the unity of the creator and redeemer God); Athanasius, Against the Gentiles; Basil of Caesarea, On the Holy Spirit; Gregory of Nazianzus, Theological Orations (esp. III–V); Augustine, On the Trinity I–IV

The patristic settlement on the one God of the creed is the doctrine of the Trinity itself. The early apologists (Justin Martyr, Theophilus of Antioch, Athenagoras) defended Christian monotheism against pagan polytheism by appeal to philosophical-Jewish monotheism. The anti-Gnostic theologians (Irenaeus, Tertullian) defended the one God by insisting that the God of creation and the God of redemption are the same God, against Marcion’s two-god theology. The fourth-century controversies forced the deepest formulation: the one God is Father, Son, and Holy Spirit, three persons in one substance (Latin: tres personae, una substantia; Greek: treis hypostaseis, mia ousia).

Augustine’s On the Trinity is the great Latin patristic synthesis. Augustine’s discipline is to begin with the one God of the Old and New Testaments and to think the threeness from within the oneness — not three gods who happen to be united, but one God whose eternal life is the communion of Father, Son, and Spirit. The Cappadocian framework (the one divine ousia possessed simultaneously by the three hypostaseis) and the Augustinian framework (the one divine being whose internal relations are the persons) name the same mystery from different angles, and the East and the West have together insisted that neither framework collapses the one into three or the three into a featureless one.

Strengths

• Holds Jewish monotheism and trinitarian confession together as the same doctrine
• The patristic distinction between ousia and hypostasis preserves both unity and distinction
• Augustine and the Cappadocians together form the foundation of the catholic doctrine of God

Weaknesses

• The Greek philosophical vocabulary (ousia, hypostasis) was always under strain to do biblical work it was not natively designed to do
• Some patristic articulations leaned more toward speculation than the texts themselves warrant

Scholastic

Tradition: Anselm, Monologion; Thomas Aquinas, Summa Theologiae I.2–11 (on the existence and nature of God) and I.27–43 (on the Trinity); Bonaventure, Itinerarium mentis in Deum

The scholastic tradition systematized the patristic confession of the one God under two heads: de Deo uno (on the one God) and de Deo trino (on the triune God). The order is not arbitrary: Aquinas’s Summa I.2–26 treats the one God’s existence, simplicity, perfection, goodness, infinity, immutability, eternity, and unity before turning to the trinitarian processions in I.27. The order is sometimes criticized as importing a philosophical-monotheistic frame that distorts the trinitarian confession; the better reading is that Aquinas is unfolding what the creedal one God already contains, with the trinitarian specification given in the second movement. The one God of Aquinas’s first movement is not a philosophical abstraction but the one God of the Christian creed — whose unity and whose three-ness are one doctrine, treated in two sequential movements for pedagogical reasons.

Anselm’s Monologion gives the medieval Latin meditation on the one God in conversation with the Augustinian tradition. Bonaventure’s Itinerarium names the one God as the goal of the soul’s ascent — the unum necessarium (the one thing necessary) of Luke 10:42.

Strengths

• The order de Deo uno → de Deo trino preserves the conciliar logic: monotheism is the framework within which the trinitarian confession is given
• Aquinas’s careful articulation of the divine attributes (simplicity, eternity, immutability, etc.) provides a vocabulary the modern church still needs
• Bonaventure’s spiritual register reconnects the doctrine to the soul’s actual life

Weaknesses

• The strong philosophical articulation has occasionally been criticized (e.g. by Karl Rahner) as having decoupled the one God of theology from the trinitarian one God of the gospel
• The Aristotelian categories on which much of the scholastic articulation depends are not native to scripture and require translation

Lutheran

Tradition: Luther, Large Catechism (esp. on the first article); Augsburg Confession Art. I; Formula of Concord, Epitome Art. I

The Lutheran tradition has held the one God confession in straightforward catholic form. The Augsburg Confession (Article I) begins by reaffirming the Nicene confession verbatim: one divine essence which is called and which is truly God; eternal, without body, indivisible, of infinite power, wisdom, and goodness, the creator and preserver of all things visible and invisible; and yet there are three persons of the same essence and power. Luther’s Large Catechism on the first article of the creed (which Luther treated using the Apostles’ rather than the Nicene structure) names the practical implication: to have a god is to have something on which the heart hangs and rests for all good. The one God is the one in whom the heart actually rests — and the question Luther forces on the reader is whether the heart actually rests in the one God of the creed or in some other ultimate that has crept into the place where God should be. Luther’s anti-idolatry register is, in the Lutheran tradition, the working implication of the one God clause.

Strengths

• The pastoral reduction (to have a god is to have something on which the heart hangs) is a permanently usable teaching device
• The Lutheran articulation reaffirms the catholic substance without scholastic accretions

Weaknesses

• The Lutheran tradition’s strong concentration on the first commandment / first article connection has occasionally produced popular piety more attentive to the right object of trust than to the full trinitarian dogma the creed unfolds

Reformed

Tradition: Calvin, Institutes I.10–13 (on the knowledge of God the creator and on the Trinity); Heidelberg Catechism QQ. 24–25; Westminster Confession Ch. 2; Belgic Confession Art. 1–2

Calvin’s treatment in Institutes I.10–13 holds the one God and the Trinity together as a single doctrine. The Reformed tradition has been particularly insistent that the one God of the Christian confession is the one God of Israel — that there is no two-stage history in which Christians worship a different God from the God of the patriarchs and prophets. The Belgic Confession (1561) opens with the affirmation of one only simple and spiritual Being, which we call God; the Westminster Confession (1646) gives a sustained articulation of the divine attributes of the one God before turning to the Trinity. The Heidelberg Catechism’s pastoral register — Q. 24: How are these articles divided? A. Into three parts: the first is of God the Father and our creation; the second of God the Son and our redemption; the third of God the Holy Spirit and our sanctification — preserves the trinitarian structure of the one God confession in the form of catechesis.

Strengths

• Holds the unity-of-the-testaments emphasis firmly: the one God of the church is the one God of Israel
• The catechetical structure (Father/Son/Spirit; creation/redemption/sanctification) is pedagogically clean
• Calvin’s articulation in the Institutes I.10–13 is a permanent Reformed resource

Weaknesses

• The Reformed accent on the divine attributes has occasionally produced popular piety more attentive to the one than to the three
• The strong polemical context of the Reformation occasionally produced articulations sharper than the catholic substance required

Eastern Orthodox

Tradition: Basil of Caesarea, On the Holy Spirit; Gregory of Nazianzus, Theological Orations III–V; John of Damascus, On the Orthodox Faith I; Vladimir Lossky, The Mystical Theology of the Eastern Church

The Eastern tradition has consistently insisted on what is sometimes called the monarchy of the Father — the Father is the unique source (archē, pēgē, aitia) of the divine life, from whom the Son is eternally begotten and the Spirit eternally proceeds. The Eastern one of the creed is the one Father whose eternal life is shared without remainder with the Son and the Spirit. This is not a subordinationist articulation; the Father, Son, and Spirit are equally and identically the one God, but their order (taxis) in the Trinity has the Father as the unique source. The Eastern articulation has been particularly careful to keep the one of the creed pastoral and doxological — the one God is known not by speculative analysis but by liturgical participation and ascetic-mystical communion.

John of Damascus’s On the Orthodox Faith I is the great Eastern patristic synthesis. Vladimir Lossky’s Mystical Theology of the Eastern Church (1944) is the seminal modern Orthodox introduction.

Strengths

• The monarchy-of-the-Father framework keeps the trinitarian doctrine from collapsing into a generic philosophical monotheism
• The doxological-mystical register has preserved the doctrine as a living confession
• The Eastern tradition has been the most consistent defender of the original 381 form of the creed without the filioque

Weaknesses

• The strong monarchy-of-the-Father language has occasionally been heard, in the West, as veering toward subordinationism (a hearing the Eastern fathers themselves resisted)
• The strong mystical-apophatic register can be hard to translate for cultures unfamiliar with the patristic-monastic tradition

Wesleyan

(See Wesleyan Voice below.)

Modern Ecumenical

Tradition: Karl Barth, Church Dogmatics I/1 §§8–12; Karl Rahner, The Trinity (1967); Robert W. Jenson, Systematic Theology I (1997); Sarah Coakley, God, Sexuality, and the Self (2013)

The 20th-century theological recovery has produced one of the great periods of trinitarian theology in the history of the church. Barth’s Church Dogmatics I/1 reopens the dogma of the Trinity as the doctrine of the one God from within revelation, against every approach that begins from a generic concept of God and then tries to fit a trinitarian addendum. Rahner’s The Trinity (1967) names what he calls the Grundaxiom — the economic Trinity is the immanent Trinity, and the immanent Trinity is the economic Trinity — the methodological claim that the one God we know in the history of salvation is the one God who eternally is, and not a different (more hidden, more abstract) God behind that history. Jenson’s Systematic Theology I (1997) gives the most sustained American articulation of the trinitarian one. Coakley’s God, Sexuality, and the Self (2013) recovers the contemplative-pneumatological register of the one God against rationalist accounts.

Strengths

• Has decisively restored the doctrine of the Trinity to its place as the doctrine of the one God, against a long modern tendency toward generic monotheism
• Rahner’s Grundaxiom has reshaped the way the doctrine is taught across the Western confessions
• Coakley’s contemplative recovery has reconnected the doctrine to the actual prayer of the church

Weaknesses

• Some modern reconstructions of the Trinity (especially in popular form) have leaned toward social-trinitarian framings that risk a tri-theistic hearing the creed itself refuses
• The methodological emphasis on the economic Trinity has occasionally produced articulations that lose the eternal-immanent dimension the creed clearly intends

Wesleyan Voice

Wesley’s confession of the one God of the Christian Trinity is unambiguous, traditional, and at the center of his theology. The Methodist Articles of Religion (1784), Article I, opens with what is essentially a paraphrase of the Nicene confession of the one God: There is but one living and true God, everlasting, without body or parts, of infinite power, wisdom, and goodness; the maker and preserver of all things, both visible and invisible. And in unity of this Godhead there are three persons, of one substance, power, and eternity — the Father, the Son, and the Holy Ghost. Wesley’s Article I is, almost word for word, the Article I of the Anglican Thirty-Nine Articles (1571) that he received and trimmed for American Methodist use; it is itself a near-translation of the Augsburg Confession’s Article I; and the Augsburg’s Article I is itself a near-paraphrase of the Nicene Creed. The chain of inheritance is unbroken.

Wesley’s most sustained pastoral statement on the doctrine of the Trinity is Sermon 55, “On the Trinity,” preached on 1 John 5:7 (the Comma Johanneum, which Wesley accepted; the contemporary church should be aware that the text is now generally regarded as a later interpolation, but the doctrine the sermon defends does not depend on the verse). Wesley’s argument in the sermon is precisely the Nicene one: the one God of the Christian confession is the one God who is Father, Son, and Holy Spirit, and this doctrine — though I do not pretend to be able to explain — is essential to Christian faith because it is the form of the gospel itself. Wesley’s careful pastoral move is to insist on the fact of the trinitarian confession while refusing to require the believer to explain what cannot be explained. The believer is not asked to comprehend the inner life of God; the believer is asked to confess the God who has revealed himself as Father, Son, and Spirit, and to entrust her life to that God.

What is distinctively Wesleyan is the experiential-relational register of the doctrine. The Methodist ordo salutis — prevenient, justifying, sanctifying, glorifying grace — is consistently trinitarian: the Father draws, the Son redeems, the Spirit sanctifies. The Methodist class meeting was the practical site at which the believer learned to live in trinitarian communion: God the Father loved before the believer knew it, God the Son saved while the believer was still a sinner, God the Spirit is even now transforming the believer into the likeness of Christ. The one God of the Methodist confession is the one God whose love is the substance of the believer’s daily life. There is no Wesleyan monotheism that is not trinitarian, and no Wesleyan trinitarianism that is not pastoral.

The Methodist pastoral posture: confess the one God as the one God of Israel, made fully known as Father, Son, and Holy Spirit; refuse every modern attempt to soften the doctrine into a generic monotheism on one side or to inflate it into tri-theism on the other; live in the actual communion the doctrine names; teach the people the words Father, Son, and Holy Spirit in baptism and at the table and in the daily prayers, because those words are the form of the gospel.

Hymnody

The trinitarian hymnody of the Wesleyan tradition is among the richest in the church, and is in many cases the most accessible form in which the doctrine has reached ordinary Methodist piety.

“Holy, Holy, Holy! Lord God Almighty!” (Reginald Heber, 1826) is the great Trinity Sunday hymn that has crossed nearly every English-speaking confessional boundary. The hymn’s refrain — God in three persons, blessed Trinity — is the most widely sung articulation of the Nicene confession of the one God in the modern church. The hymn’s other distinctive line — only thou art holy; there is none beside thee, / perfect in power, in love, and purity — is the Nicene unum Deum in singable form.

“Come, thou almighty King” (anon., 1757, sometimes attributed to Charles Wesley) is the great mid-18th-century Trinity hymn that the early Methodist societies sang. The hymn is trinitarian by stanza — stanza 1 addresses the Father, stanza 2 the Son, stanza 3 the Spirit, stanza 4 the Triune God — and is among the most explicit hymnic articulations of the Nicene structure.

“Maker, in whom we live” (Charles Wesley, 1747) is the Wesleyan trinitarian hymn that is less widely sung today than it deserves. Its structure is exactly Trinitarian: stanza 1 to the Father (the Maker), stanza 2 to the Son (the Redeemer), stanza 3 to the Spirit (the Sanctifier), stanza 4 to the Triune God. Eternal, Triune God, / let all the hosts above, / let all on earth below record / and dwell upon thy love.

“Father, in whom we live” (Charles Wesley, 1747) is the companion Wesleyan trinitarian hymn. Both 1747 hymns are among the great catechetical achievements of Charles Wesley’s project: a song of the doctrine of the one God in three persons that the singer learns by singing.

“Doxology (“Praise God, from whom all blessings flow”)” (Thomas Ken, 1674) is the trinitarian doxology most universally sung in Methodist worship. Praise Father, Son, and Holy Ghost — the one God of the creed named in the order of the eternal life, three persons, one God.

“Gloria Patri” — the ancient Christian doxology Glory be to the Father, and to the Son, and to the Holy Spirit; as it was in the beginning, is now, and ever shall be, world without end. Amen. — is the church’s daily liturgical confession of the one God in three persons. The early Methodist societies sang it; the United Methodist Hymnal preserves it; it should not disappear from Methodist worship.

Pastoral and Liturgical Use

The one God clause is not, in modern Western secular cultures, the controversial clause it once was. The pagan pantheon is no longer a live alternative. The Marcionite two-god theology has no contemporary advocates. The question for the modern Methodist parish is therefore not one God or many gods. The question is whether the one God the congregation actually has — the operative ultimate around which lives are actually arranged — is the one God the creed names.

The most pastorally useful reading of this clause is therefore the one Luther gave it: to have a god is to have something on which the heart hangs and rests for all good. The modern person almost always has a god, in this functional sense. The question is which one. The mortgage. The 401(k). The career. The family system. The political tribe. The romantic relationship. The body image. The validation of the algorithm. These functional gods are not always evil; some of them are good things that have been raised to a place they cannot bear. But they are not the one God the creed confesses, and they cannot do what the one God of the creed does. They cannot raise the dead. They cannot forgive sins. They cannot make a covenant of love that holds when everything else fails. They cannot keep their promises through death. The first clause of the Nicene Creed asks the church the most ancient and the most contemporary question at once: what god do you actually have?

The Nicene we believe matters here. The Christian confession is not the private act of an individual who has reasoned her way to monotheism; it is the corporate confession of the church into which baptism has incorporated the believer. The believer does not stand alone before a hostile pantheon, deciding which of the many available ultimates to credit. The believer stands within the church, joining her voice to a we that has been speaking this confession in every generation since Nicaea, and in earlier forms since the Shema. The creedal we is the support the modern Methodist needs against the relentless cultural pressure to construct her own private deity. We believe in one God — and the we is the church, across time and space, and the one God is the one God the prophets confessed and Jesus prayed to and Paul preached and the bishops at Nicaea defined and Wesley sang of and the Spirit even now is naming in the believer’s heart.

A teaching device worth keeping in front of a Methodist parish: if there is one God, there is one history. The temptation, in a fragmented culture, is to live as if there were many histories — a private history of the family, a political history of the nation, a religious history of the church, a personal history of the self — each in its own register, each governed by its own ultimate. The Nicene confession of one God refuses the fragmentation. The God who is creator of heaven and earth, the God who became incarnate of the Virgin Mary, the God whose Spirit is even now at work in the believer, the God who will raise the dead at the last day — this God, the one God of the creed, is the God whose providence is the actual ordering of every life. The fragmentation is the illusion. There is one history, because there is one God. Every history is the one history of the one God’s work, and the believer’s life is part of it.

The creedal one also bears on Christian relations with Judaism and Islam, the other great monotheisms. The one God the Christian confesses is the one God of Abraham, Isaac, and Jacob — the same God Jews still confess in the Shema. The Christian confession of the Trinity is not a departure from Jewish monotheism but the Christian church’s specification of what the one God of Israel has now revealed himself to be: the God whose eternal life is the communion of Father, Son, and Holy Spirit, and who has come to the nations in his Son and his Spirit. The relation to Islam is more complex (the Qur’an explicitly contests the trinitarian articulation), but the one God remains the shared confession across the Abrahamic monotheisms in a way that should produce both clarity and humility in Christian witness. The pastor who teaches the one God clause well will teach the congregation to hear the Shema as part of her own confession, and to think carefully about what the doctrine of the Trinity actually does and does not add.

For the preacher: do not rush past the first word of the creed. We is the gift; one is the boundary; God is the substance. We — the church into which we have been incorporated by baptism. One — the refusal of every idol, ancient and modern, that would compete with the God of Israel for the heart’s allegiance. God — the God who has actually made and saved and is sanctifying the world. The first clause of the Nicene Creed is the foundation on which everything that follows rests, and the church needs it as much in this generation as in any.

Further Reading

• Deuteronomy 6:4–9 — the Shema, the foundational confession of the one God of Israel
• Isaiah 40–55 — the prophetic articulation of the one God against the gods of the nations
• Mark 12:28–34 — Jesus on the great commandment, reaffirming the Shema
• John 17 — the Johannine articulation of the unity of the Father and the Son
• 1 Corinthians 8:1–6 — for us there is one God, the Father, from whom are all things, and one Lord, Jesus Christ, through whom are all things
• 1 Timothy 2:5 — there is one God, and there is one mediator
• Ephesians 4:4–6 — one Lord, one faith, one baptism, one God and Father of all
• James 2:19 — you believe that God is one; you do well
• Irenaeus, Against Heresies I–II (the unity of creator and redeemer against Marcion)
• Athanasius, Against the Gentiles (the one God against the pagan pantheon)
• Basil of Caesarea, On the Holy Spirit
• Gregory of Nazianzus, Theological Orations III–V
• Augustine, On the Trinity (the great Latin patristic synthesis)
• John of Damascus, On the Orthodox Faith Book I
• Anselm of Canterbury, Monologion; Proslogion
• Thomas Aquinas, Summa Theologiae I.2–43 (the medieval Latin synthesis on the one God and the Trinity)
• Martin Luther, Large Catechism on the first article; Augsburg Confession, Article I
• John Calvin, Institutes of the Christian Religion I.10–13
• Heidelberg Catechism QQ. 24–25
• Westminster Confession of Faith, Chapter 2
• Belgic Confession (1561), Articles 1–2
• Articles of Religion of the Methodist Church (1784), Article I
• John Wesley, Standard Sermons, Sermon 55 (“On the Trinity”)
• John Wesley, Explanatory Notes upon the New Testament on 1 Corinthians 8 and 1 Timothy 2
• Charles Wesley, “Maker, in whom we live” (1747); “Father, in whom we live” (1747)
• Reginald Heber, “Holy, Holy, Holy! Lord God Almighty!” (1826)
• Karl Barth, Church Dogmatics I/1 §§8–12
• Karl Rahner, The Trinity (Herder, 1970; original German 1967)
• Vladimir Lossky, The Mystical Theology of the Eastern Church (1944)
• Robert W. Jenson, Systematic Theology, Vol. 1: The Triune God (Oxford, 1997)
• Sarah Coakley, God, Sexuality, and the Self (Cambridge, 2013)
• Catherine Mowry LaCugna, God for Us: The Trinity and Christian Life (HarperOne, 1991)