The Doctrine of the Trinity: No Christianity Without It

If any doctrine makes Christianity Christian, then surely it is the doctrine of the Trinity. The three great ecumenical creeds—the Apostles’ Creed, the Nicene Creed, and the Athanasian Creed—are all structured around our three in one God, underlying the essential importance of Trinitarian theology. Augustine once commented about the Trinity that “in no other subject is error more dangerous, or inquiry more laborious, or the discovery of truth more profitable.” More recently, Sinclair Ferguson has reflected on “the rather obvious thought that when his disciples were about to have the world collapse in on them, our Lord spent so much time in the Upper Room speaking to them about the mystery of the Trinity. If anything could underline the necessity of Trinitarianism for practical Christianity, that must surely be it!”

Yet, when it comes to the doctrine of the Trinity, most Christians are poor in their understanding, poorer in their articulation, and poorest of all in seeing any way in which the doctrine matters in real life. One theologian said, tongue in cheek, “The trinity is a matter of five notions or properties, four relations, three persons, two processions, one substance or nature, and no understanding.” All the talk of essence and persons and co-this and co-that seem like theological gobbledy-gook reserved for philosophers and scholars-maybe for thinky bookish types, but certainly not for moms and mechanics and middle-class college students.

So in a few hundred words let me try to explain what the doctrine of the Trinity means, where it is found in the Bible, and why it matters.

First, what does the doctrine mean? The doctrine of the Trinity can be summarized in seven statements. (1) There is only one God. (2) The Father is God. (3) The Son is God. (4) The Holy Spirit is God. (5) The Father is not the Son. (6) The Son is the not the Holy Spirit. (7) The Holy Spirit is not the Father. All of the creedal formulations and theological jargon and philosophical apologetics have to do with safeguarding each one of these statements and doing so without denying any of the other six. When the ancient creeds employ extra-biblical terminology and demand careful theological nuance they do so not to clear up what the Bible leaves cloudy, but to defend, define, and delimit essential biblical propositions. The Athanasian Creed puts it this way: “Now this is the catholic faith: That we worship one God in trinity and the trinity in unity, neither blending their persons, nor dividing their essence. For the person of the Father is a distinct person, the person of the Son is another, and that of the Holy Spirit, still another. But the divinity of the Father, Son, and Holy Spirit is one, their glory equal, their majesty coeternal.”

The two key words here are essence and persons. When you read “essence”, think “Godness.” All three Persons of the Trinity share the same “Godness.” One is not more God than another. None is more essentially divine than the rest. When you read “persons”, think “a particular individual distinct from the others.” Theologians use these terms because they are trying to find a way to express the relationship of three beings that are equally and uniquely God, but not three Gods. That’s why we get the tricky (but learnable) language of essence and persons. We want to be true to the biblical witness that there is an indivisibility and unity of God, even though Father, Son, and Holy Spirit can all be rightly called God. The Persons are not three gods; rather, they dwell in communion with each other as they subsist in the divine nature without being compounded or confused.

Sometimes it’s easier to understand what we believe by stating what we don’t believe.

• Orthodox Trinitarianism rejects monarchianism which believes in only one person (mono) and maintains that the Son and the Spirit subsists in the divine essence as impersonal attributes not distinct and divine Persons.
• Orthodox Trinitarianism rejects modalism which believes that Father, Son, and Holy Spirit are different names for the same God acting in different roles or manifestations (like the well-intentioned but misguided “water, vapor, ice” analogy).
• Orthodox Trinitarianism rejects Arianism which denies the full deity of Christ.
• And finally, orthodox Trinitarianism rejects all forms of tri-theism, which teach that the three members of the Godhead are, to quote a leading Mormon apologist, “three distinct Beings, three separate Gods.”

Second, where is the doctrine of the Trinity found in the Bible? Although the word “Trinity” is famously absent from Scripture, the theology behind the word can be found in a surprising number of verses. For starters there are verses that speak of God’s oneness (Deut. 6:4; Isa. 44:6; 1 Tim. 1:17). Then there are the myriad of passages which demonstrate that God is Father (e.g., John 6:27, Titus 1:4). Next, we have the scores of texts which prove the deity of Jesus Christ, the Son—passages like John 1 (“the word was God”), John 8:58 (“before Abraham was born, I am”), Col. 2:9 (“in Christ all the fullness of Deity lives in bodily form”), Heb. 1:3 (“The Son is the radiance of God’s glory and the exact imprint of his being”), Tit. 2:13 (“our great God and Savior Jesus Christ”)-not to mention the explicit worship Christ willingly received from his disciples (Luke 24:52; John 20:28) and the charges of blasphemy leveled against him for making himself equal with God (Mark 2:7). Then we have similar texts which assume the deity of the Holy Spirit, calling Him an “eternal Spirit” (Heb. 9:14) and using “God” interchangeably with the “Holy Spirit” (1 Cor. 3:16 and 1 Cor. 6:19; Acts 5:3-4) without a second thought.

The shape of Trinitarian orthodoxy is finally rounded off by texts that hint at the plurality of persons in the Godhead (Gen. 1:1-3, 26; Psalm 2:7; Dan. 7), texts like 1 Cor. 8:6 which place Jesus Christ as Lord right in the middle of Jewish Shema, and dozens of texts that speak of the Father, Son, and Holy Spirit in the same breath, equating the three in rank, while assuming distinction of personhood (Matt. 28:19; Gal. 4:6; 1 Cor.12:4-6; 1 Peter 1:1-2; 2 Cor. 2:21-22; 13:14; Eph. 1:13-14; 2:18, 20-22; 3:14-17; 4:4-6; 5:18-20; 6:10-18).

The doctrine of the Trinity, as summarized in the seven statements earlier, is not a philosophical concoction by some over-zealous and over-intelligent early theologians, but one of the central planks of orthodoxy which can shown, explicitly or implicitly, from a multitude of biblical texts.

Third, why does any of this matter? There are lots of reasons, but borrowing from Robert Letham’s work, and in Trinitarian fashion, let me mention just three.

One, the Trinity matters for creation. God, unlike the gods in other ancient creation stories, did not need to go outside himself to create the universe. Instead, the Word and the Spirit were like his own two hands (to use Irenaeus’ famous phrase) in fashioning the cosmos. God created by speaking (the Word) as the Spirit hovered over the chaos. Creation, like regeneration, is a Trinitarian act, with God working by the agency of the Word spoken and the mysterious movement of the Holy Spirit.

Two, the Trinity matters for evangelism and cultural engagement. I’ve heard it said that the two main rivals to a Christian worldview at present are Islam and Postmodernism. Islam emphasizes unity—unity of language, culture, and expression—without allowing much variance for diversity. Postmodernism, on the other hand, emphasizes diversity—diversity of opinion, belief, and background—without attempting to see things in any kind of meta-unity. Christianity, with its understanding of God as three in one, allows for diversity and unity. If God exists in three distinct Persons who all share the same essence, then it is possible to hope that God’s creation may exhibit stunning variety and individuality while still holding together in a genuine oneness.

Three, the Trinity matters for relationships. We worship a God who is in constant and eternal relationship with himself as Father, Son, and Holy Spirit. Community is a buzz word in American culture, but it is only in a Christian framework that communion and interpersonal community are seen as expressions of the eternal nature of God. Likewise, it is only with a Trinitarian God that love can be an eternal attribute of God. Without a plurality of persons in the Godhead, we would be forced to think that God created humans so that he might show love and know love, thereby making love a created thing (and God a needy deity). But with a biblical understanding of the Trinity we can say that God did not create in order to be loved, but rather, created out of the overflow of the perfect love that had always existed among Father, Son, and Holy Spirit who ever live in perfect and mutual relationship and delight.