Trinity

“Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.”

— Matthew 28:19

The Trinity is the doctrine that the one true God eternally exists as three distinct persons, Father, Son, and Holy Spirit, each fully and equally God, sharing one undivided divine essence. The three persons are not three gods, and they are not three roles played by one person; each is fully God, yet there is only one God.¹

Confessional Definition

The 1689 Second London Baptist Confession states the doctrine directly: “In this divine and infinite Being there are three subsistences, the Father, the Word or Son, and Holy Spirit, of one substance, power, and eternity, each having the whole divine essence, yet the essence undivided.”² The confession then distinguishes the three by their relations of origin rather than by any difference in nature: “the Father is of none, neither begotten nor proceeding; the Son is eternally begotten of the Father; the Holy Spirit proceeding from the Father and the Son.”²

The word “subsistences” is doing careful work here. Bavinck explains that in the church’s settled usage, “person” in this doctrine does not mean a separate center of consciousness the way it does when applied to three different human beings; it means only that the Father, Son, and Spirit each have “a distinct existence of their own” within the one divine being, not that the being is divided into three parts or that “person” is merely a mask or mode assumed by one underlying self.¹ The confession draws the implication directly: because the three subsistences share one undivided essence, “all infinite, without beginning,” they are “but one God, who is not to be divided in nature and being, but distinguished by several peculiar relative properties and personal relations.” The confession adds that this is no mere abstraction: the doctrine of the Trinity “is the foundation of all our communion with God, and comfortable dependence on him.”² How the Son’s eternal generation and the Spirit’s procession are themselves to be understood, including the historic Eastern/Western disagreement over whether the Spirit proceeds from the Father alone or from the Father and the Son, is the filioque question.

Biblical Basis

Scripture nowhere states the doctrine of the Trinity as a formula, but it presents a threefold divine agency from its opening pages. Creation comes by the word of God (Gen. 1:3), by the Spirit of God hovering over the waters (Gen. 1:2), and by Wisdom personified alongside God (Prov. 8:22-31); the LORD reveals and saves his people by his word and his Spirit throughout the Old Testament.¹ The New Testament makes the threefold pattern explicit and personal. Jesus commands baptism “in the name of the Father and of the Son and of the Holy Spirit,” one singular “name” shared by three (Matt. 28:19). Paul closes a letter with a three-part benediction naming all three as the source of grace, love, and fellowship alike (2 Cor. 13:14). John opens his Gospel by identifying the Word both as distinct from God (“the Word was with God”) and as God himself (“the Word was God”), before saying the Word “became flesh” in Jesus (John 1:1, 14). At Jesus’ baptism, the Father speaks from heaven, the Son is baptized, and the Spirit descends as a dove, all three present and active at once (Matt. 3:16-17).

Historical Development

The development of Trinitarian theology runs from the earliest Christological controversies to the settled Nicene language. Arius taught that the Son was a creature, “other than the Father in substance,” brought into being by the Father’s will rather than sharing his eternal nature.³ The Council of Nicaea (AD 325) rejected this and affirmed the Son’s full deity, which changed the shape of the debate that followed: “before Nicaea the main difficulty was to derive a threesome from the oneness of God; after Nicaea the reverse is true.”³ Athanasius, chief defender of the Nicene decision, “understood better than any of his contemporaries that Christianity stands or falls with the confession of the deity of Christ and the Trinity; it is the heart and center of Christianity.”³ The Council of Constantinople (AD 381) completed the settlement by affirming the full deity of the Holy Spirit alongside the Father and the Son.

Objections and Responses

If the Father, Son, and Spirit are each fully God, doesn’t that make three Gods? This is the charge of tritheism, and it rests on treating “person” in this doctrine the way the word applies to three separate human beings, each with their own individual nature. But the three divine persons don’t each have a separate divine nature the way three people each have a separate human nature; they share one and the same undivided divine essence, “one eternal, omnipotent, and omniscient being, having one mind, one will, and one power.”¹ Human analogies to the Trinity should be used with real caution for exactly this reason, since pressed too far they suggest three separate beings rather than one.¹

If Father, Son, and Spirit are one God, aren’t they just three names or modes for the same person? This is modalism, and the confession’s choice of the word “subsistences” instead of “modes” is aimed directly at it. The three are not successive masks or roles worn by one underlying self; each has, in Bavinck’s phrase, “a distinct existence of their own” within the one divine being, and Scripture presents them acting distinctly and simultaneously, as at Jesus’ baptism, where the Father speaks, the Son is baptized, and the Spirit descends, all at the same moment (Matt. 3:16-17).¹

Related Doctrines

References

Herman Bavinck, Reformed Dogmatics: Abridged in One Volume, ed. John Bolt (Grand Rapids: Baker Academic, 2011), chap. 9, “The Triune God and His Counsel.” ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶
The Second London Baptist Confession of Faith (1689), chap. 2, “Of God, and of the Holy Trinity,” para. 3. ↩ ↩² ↩³
Bavinck, Reformed Dogmatics, chap. 9, “The Triune God and His Counsel.” ↩ ↩² ↩³