Tertullian (c. 160-220 AD) is officially given credit for coining the term “Trinity” to refer to the triune nature of the Godhead (Father, Son, and Holy Spirit).

The Biblical text, specifically the NT, references the Father, Son, and Spirit in about 120 different passages (e.g. Matt 28:18-20; Jn 14-17; Acts 2:32-33, etc.), though not all references use the three together.

While “Trinity” is not actually used in the Scripture, all orthodox Christian traditions have accepted the term as a sufficient way of describing the three-in-one relationship of God, including my own denomination, the MCUSA.

Those that don’t embrace Trinitarian theology are Unitarians, Jehovah’s Witnesses, Oneness Pentecostals, Mormons, Christian Scientists, etc. According to orthodoxy, these so-called “Christian” groups are heretical (or cultic) for being anti-Trinitarian, and for other reasons related to Christology.

The Trinity Revealed by Jesus & the Apostles

I’ve heard skeptics and YouTube atheists claim that Constantine is responsible for belief in the Trinity, and for it becoming the orthodox position. Is this true?

It’s true that the Trinity was further articulated and defended by folks like Athanasius at the Council of Nicaea in the 4th century, but it was by no means an “invented” doctrine of the church. Constantine’s concern was merely for the bishops to settle the theological dispute brought on by Arianism. Yes, he did want unity in his new empire, but the imperial decision was for Christendom’s growing hold on the world, it was nothing new for Christian theology.

On the contrary, Polycarp (69-155 AD), bishop of Smyrna and disciple of the apostle John, expressed Trinitarian belief when he wrote the following:

“O Lord God almighty… I bless you and glorify you through the eternal and heavenly high priest Jesus Christ, your beloved Son, through whom be glory to you, with Him and the Holy Spirit, both now and forever” (n. 14, ed. Funk; PG 5.1040).

The ante-Nicene church fathers used Trinitarian language unambiguously in their writings. This includes Justin Martyr, Ignatius of Antioch, Irenaeus, and Origen. And as previously stated, it was Tertullian in the late second century that identified the communal concept of God as “Trinity” to capture his essence.

Therefore, the Nicene Creed reflects the earliest Christian confession about the Father, Son, and Holy Spirit, dating back to Jesus and the apostles themselves.

The Trinity as Christian Dogma

Despite the mysterious complexity of the Trinity, orthodox Christianity has considered it dogma since the very beginning. The one true God is triune. In other words, there is no room for “variance” or disagreement.

Augustine of Hippo (354-430 AD) once quipped, “If you try to understand the Trinity, you will lose your mind. If you deny the Trinity you will lose your soul.”

While I personally believe that folks can trip up on this doctrine and still know the salvation God offers in Jesus, I understand Augustine’s primary point to be this: The Trinity is a non-negotiable biblical truth.

In Theology for the Community of God (p.53), Stanley Grenz wrote:

“Of the various aspects of our Christian understanding of God perhaps none is as difficult to grasp as the concept of God as triune. At the same time, no dimension of the Christian confession is closer to the heart of the mystery of the God we have come to know. In fact, what sets Christianity apart from the other religious traditions is the confession that the one God is Father, Son, and Spirit. As a consequence, no teaching lies at the center of Christian theology, if not of Christian faith itself, as does the doctrine of the Trinity.”

So, Augustine is right about the Trinity being a non-negotiable element of our faith. However, I’m certain that much about the triune God can be understood, and should be understood for faith and practice. And many trusted theologians throughout church history have offered helpful insights.

The Foundation for Belief in a Triune God

One of the most logical and practical insights into the triune God begins with the universally celebrated Christian confession: “God is love” (1 John 4:8, 16). OK, how can we know that? More specifically, why does John believe it?

Listen to his answer: “This is how God showed his love among us: He sent his one and only Son into the world…” (1 Jn 4:9a NIV). John is saying that “God is love” and we can know it because Jesus has revealed God in all of his fullness!

Robert Barron, Catholic thinker and practitioner, says, “Love isn’t just something God does, it’s who God is.”  Think about that.

I believe after serious reflection, our confession that “God is love” can be recognized as the very foundation by which the apostles believed in the triune God. And from this God comes our understanding of the church in his image.

Listen to Barron explain how confessing “God is love” makes a triune God necessary and coherent for a truly liberating and practical theology.

What do you think of Barron’s explanation of God as lover (Father), the beloved (Son), and the love (Spirit) shared between them? How else does the Trinity matter for Christian belief and practice?

D.D. Flowers, 2014.

For further study, see my article: Trinity & Incarnation: Finding a Biblical Christology Within a Trinitarian Monotheism (2011).

Suggested Reading:

• Theology for the Community of God by Stanley Grenz (pgs. 53-95)
• The Trinity & the Kingdom by Jürgen Moltmann
• After Our Likeness: The Church as Image of the Trinity by Miroslav Volf
• God in New Testament Theology by Larry Hurtado (pgs. 27-47)
• A Contemporary Anabaptist Theology by Thomas Finger (pgs. 423-464)