This post was adapted from my lesson during Equipping Hour at Sovereign Grace Bible Church on April 7, 2019. This is the first post in a series of two.

There are several doctrines of the Christian faith that leave us asking, “Now what does that mean again?” We find that since these doctrines are so bewildering we might as well not attempt to understand them as fully as we can.

Well, the Trinity is one of those doctrines.

In this post, not only do I seek to define the Trinity, but contrast it with a heretical view and explain why it’s an essential doctrine of the Christian faith. My next post will be specifically about how the Trinity applies to our lives.

What is the Trinity?

The 1689 Second London Baptist Confession of Faiths defines the Trinity this way:

“This divine and infinite Being consists of three real persons, the Father, the Word or Son, and the Holy Spirit. These three have the same substance, power, and eternity, each having the whole divine essence without this essence being divided. The Father is not derived from anyone, neither begotten nor proceeding. The Son is eternally begotten of the Father. The Holy Spirit proceeds from the Father and the Son. All three are infinite and without beginning and are therefore only one God, who is not to be divided in nature and being. Yet these three are distinguished by several distinctive characteristics and personal relations. This truth of the Trinity is the foundation of all of our fellowship with God and of our comforting dependence on him” (Chapter 2, 3rd point).

In other words, God is one Being that exists in three Persons: Father, Son, Spirit. They are all equally God in every way, shape, and form. Though they have different roles, they nevertheless are of the same nature and substance. Remember this: three Persons, one Being—not three beings (that would be three gods).

There are numerous texts of Scripture that point to the triune nature of God, but in my opinion, no text does that better than Matthew 28:19–the Great Commission: “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” (italics added).

The reason I think this is the best text on the Trinity is not only because it mentions all three Persons, but it says “in the name of.” Notice this is singular, not plural. It doesn’t say, “in the names of.” I think this clearly points to there being only one God yet existing in three Persons.

Contrasting with Modalism

Modalism (or Oneness Pentecostalism) is very sneaky. This heresy seeks to collapse the Godhead into only one Person. In this teaching, God is in fact Father, Son, and Holy Spirit–but not simultaneously. In this view, God only manifests Himself in these different roles. They are not three distinct Persons.

A good way of saying it is that God was the Father in the Old Testament, the Son in the New Testament, and the Spirit now. Of course, that has massive holes in it. What do you do with the baptism of Jesus, for starters, where all three Persons are present? Modalism falls apart.

Image from Dank Theological Memes

With this issue comes the problem of attempting to provide analogies for the Trinity. A popular one is the water analogy (liquid, gas, solid).

The analogy goes like this: the matter (water) has three different forms: liquid, gas, and solid. Hence, we try to say that is an example of three-in-one.

However, here’s the problem: liquid water, when freezes, switches to ice. It becomes ice. But the different Persons of the Trinity don’t become each other. This matter manifests itself in different forms–God does not.

A word of advice: simply avoid using alagoies for the Trinity. We are finite, God is infinite. It’s better for us to explain the biblical view and admit that no analogy will ever suffice. I believe it’s better to stand in awe of the absolute complexity of God’s nature insofar as it pertains to us understanding it.

Another issue pertaining to Modalism is that many immature Christians probably would define the Trinity this way when asked. Does that mean they aren’t saved? Not necessarily.

My point is, many well-meaning Christians probably have an erroneous view of the Trinity because it seems like such an abstract concept to them. It’s certainly possible for a Christian—for an extended time—to have a bad view of the Trinity and then learn the correct view. However, if a person actively believes that God manifests in different forms, then that person is not saved. In other words, if they know the difference between Modalism and the biblical view of the Trinity, yet still agree with the Modalistic teaching, then they are not Christian.

Why It’s Essential

The doctrine of the Trinity is essential for us to believe in because it’s imperative in our knowledge of God. If we don’t believe in the Trinity, we don’t know God.

This doctrine separates biblical Christianity from practically all other religions. We distinguish ourselves from Judaism, Islam, Mormonism, and the rest.

We will never fully exhaust how complex the Trinity is. We will never fully wrap our minds around it, not even in Heaven. When we reach Heaven, we will never stop learning more things about who God is. His character and nature is inexhaustible.

Let that be a good thing.

Next, I will write about how we experience the Trinity.

Soli Deo Gloria