Trinity: The One God's Threeness

I. The Risky, Indispensable Doctrine of the Trinity
Israel confesses YHWH as one (Deut 6:4).

Christians develop the doctrine of God's Trinity ('Tri-unity')

to speak about God in light of Jesus Christ (for whom Father and Spirit are both other and one),
to guard the apostolic traditions and insights, and
to guide further exploration of God and God's works.

II. Is 'Trinity' Biblical?
The Old Testament only hints (Gen 18:1-16, Isa 6:3, Ps 33:6, Prov 8, Gen 1:1-3, 1:26).
Jesus reveals the God of Israel ...

... to be Father, Son, and Holy Spirit.

Jesus' and the Church's life bring God's threeness into plain view:

The Father:

Jesus calls God "the Father" (abba/ho pater; Matt 11:27).
Jesus reveals the Father (John 14:9) and does his will.

The Son:

Jesus calls himself "the (only) Son", the Father's heir (John 3:16, Rom 8:32, Col 1:13).
Jesus shows the Father as "only begotten God" (John 1:18).
Jesus is Creator, Judge, and Savior.
Believers confess that "Jesus is Lord".

The Holy Spirit:

The Spirit proceeds from the Father (John 15:26).
The Spirit conceives Jesus (Luke 1:35).
Jesus receives the Spirit from the Father (Luke 3:22, Acts 2:33).
Jesus gives the Spirit to humanity (Acts 2:33, John 14:16, 26, John 20:22)
as the Spirit's temple (confirming the Spirit's full deity).

The three together:

Explicit triads: Matt 28:19, 2 Cor 13:13.
Subtler triads: Luke 1:35, 24:49, Rom 14:17-18, 15:16, 15:30, 1 Cor 12:4-6, 2 Cor 1:21-22, 2 Cor 3:3, Gal 3:11-14, 4:6, Eph 2:18, 2:20-22, 3:14-16, Phil 3:3, Col 1:6-8, 2 Thess 2:13, Titus 3:4-6, Heb 6:4-6, 1 Pet 1:2, 4:14, 1 John 4:2, 4:13-14.

So Jews worship and serve the risen Jesus, the Father, and the Spirit as the one God of Israel.

III. Further Development in Christian Tradition
Explicit Trinitarian language develops to serve

worship practice (liturgy),
initiation (baptism) and confession (creeds),
intellectual reflection ("theology"), and
arguments against adversaries (polemics, apologetics)—
rather than mission, evangelism, or discipleship—
so not in a holistic apostolic context.

The results are two vocabularies and two models of God, crafted in response to several Trinitarian heresies.
These categories represent God technically to correct mistakes rather than inform ordinary believers, let alone outsiders.

Communicating God's reality takes practical precedence over propagating theological abstractions.

IV. Basic Trinitarian Vocabulary

in ...	one "what"	three "who's":
Greek	ousia	hypostasis
Latin	esse, substantia	persona, subsistentia
English	being, essence, substance	person, subsistence, "way of being"
but not	person, form, etc.	parts, beings, members, people, entities, forms, substances, etc.

V. Personhood Is Relational

(Review:) Harold Turner describes three anthropologies:

Atomist individualism sees humans as self-constituted, relating only coincidentally like billiard balls.
Oceanic collectivism sees masses, whose identity belongs fundamentally to their groups.
Biblical relational 'personalism' sees a net of person-making, -knowing, and -remaking interconnections.

God's Triunity is similarly relational.

We relate with the Triune God accordingly:
The church as Christ's bride is, in a sense, a person—or 'metaperson'—relating to him as a singular (Rev 22:17a).
Yet the church's members are still true persons, relating to one another and to him individually (22:17b).
Our local congregations are metapersons too, relating that way to one another and to him (22:16a, and singular verbs in Rev 2–3 alongside plurals).
And all are in Christ, included by grace in his divine personhood, sharing God’s name (22:4) and Christ’s throne (3:21), the Spirit dwelling in our one temple (3:11).

VI. Personal Being
'Cappadocian' Eastern Orthodox: The Father is the source of divinity and unity.
Augustinian Western Catholics and Protestants: God's unity is substantial: The persons share the divine essence.
Both: The persons' distinctions are relational: interrelationships constitute the Father as Father, Son as Son, Spirit as Spirit.

The legal term persona means a 'party' in relationship.
The Xhosa proverb of ubuntu (community) holds that "a person becomes a person through other persons" (umntu ngumntu ngabantu).
Scripture names relations of origin: the Son is only-begotten (John 1:14, 3:16) and the Spirit proceeds, like breath (John 15:26).

Example: It's a Wonderful Life.

The east stresses God's unity as social and dynamic
(three turned-in-mirrors) or perichoresis.

An iconic eastern illustration is Rublev's Trinity.

The west stresses the Spirit as shared between Father and Son (so the western Nicene Creed's filioque:the Spirit proceeds "also from the Son").

A western illustration is this Lakota Trinity.
Augustine explores "vestiges of the Trinity" in the human imago dei:
Lover, beloved, love; memory, intellect, will.

VII. Trinitarian Heresies Misconstrue and Scramble God's Personhood

1. Modalistic monarchianism (modalism) treats God as one source with three roles (Creator, Redeemer, Sanctifier).

Illustrations: ice-water-steam; three-leaf clover.

Personhood would be the many masks of an ancient actor (persona, prosopon).
Example: Mike Myers in Austin Powers.

Problems: Why only three?
Can you have a personal relationship with a role?
Does a role reveal an actor?
To whom does Jesus pray? (Sabellianism: persons as sequential).
Who was on the cross? (Patripassianism: "the Father suffered").
Is the cross just an act?
Wouldn't God 'need' creation to have these relationships?

Oneness Pentecostalism is modalistic.

2. Dynamic monarchianism (adoptionism) and Arianism treat the Father as the only real 'God.'

Arian illustration: sun, sunbeam, heat.

Adoptionism has Jesus inheriting 'divinity.'
Personhood means mere legal status.
The Spirit is the impersonal inheritance, sign, and seal of Jesus' adoption.
Example: Marcus Aurelius adopting Maximus in Gladiator.
Problems: What does an adopted (not begotten) Jesus show of his adoptive parent?
How is God involved on the cross?

3. Tritheism treats 'the Godhead' not as 'Godhood' but three separable 'Gods.'

Illustration: egg yolk-white-shell.

God's "unity" would merely be the moral unity of three individuals.
Personhood entails individuality, independence, consciousness (as in modern psychology).
Example: The Three Musketeers.

Problems: How does one such person reveal another?
Are Son and Spirit equal (cf. John 5:18)?
Or are they unequal (subordinationism)? (Cf. Col 1:15, John 14:28, 1 Cor 15:28, Phil 2:5-11.)
Can we divide God's glory among specific persons (cf. Deut 6:12-15)?
On the cross, is God a dysfunctional family?

Current official LDS theology conceives of 'the Godhead' tritheistically.

My advice: avoid facile analogies and pursue intimate relationships:

Follow Jesus; align with his Father's heart; invite his Holy Spirit.
Re-fill the English terms with God's reality, and use them to clarify confusions.
Don't force these understandings on others, but pass on the relationships.