|One "what" and three "whos"|
However, the title you read isn't necessarily Trinitarian—or Christian. It's true that the Triune God is both one and three, but he is one and three in a specific way. He is not one God who merely appears in three different roles in relation to creation—or who has three manifestations, as more cunning unchristians teach. A single god with three roles or manifestations is the god of modalism—and modalism was condemned as heresy a long, long time ago.
The Triune God is not three gods who work together in a unified way, either. That would be tritheism, a form of polytheism.
A Trinitarian Title
To make the title of this post specifically Trinitarian, I should have written this: God Is One Being and God Is Three Persons. That's the most common formulation of the Trinity in English—and it's precisely right, given correct definitions of the words being and person.
But the way we use those words in everyday English works against us, especially when it comes to the meaning of person. We use person to refer to separate individuals and it's difficult to see beyond that—at least it is for me. But the persons of the Trinity—Father, Son, and Holy Spirit—are not separate; they are not individuals. The three persons are always only one being. Distinct, yes; but never separate.
One What, Three Whos
I prefer to think of it like this: God is one "what" and three "whos." My pea brain grasps those terms immediately and I can understand something of God's triunity without stopping to think about proper definitions. That formulation (if we can call it that) is also a way to explain the Trinity to children without using one of the awful analogies—cloverleaf, egg, water, etc.—which are actually better illustrations of the modalist's or tritheist's god than our Triune One.
J. I Packer says that each person (He calls them "centers of self-awareness.") is "'I' in relation to two who are 'you'."1 This statement helps me, too, but it needs to be held in tension with the thought that the three "whos" are always together as one "what."
Coequal and Coeternal
There are two other English words used to express the doctrine of the Trinity. Orthodox formulations say that the three persons in the one being of God are coequal and coeternal. Father, Son, and Holy Spirit are equally God; there are no lesser gods in the Trinity. And all three persons have always existed together as God; there is no beginning or end for any of the members of the Trinity.
Safeguarding the Teaching of Scripture
These trinitarian words—person, being, coequal, coeternal, and even Trinity itself—are not used in scripture, but they are thoroughly biblical because they come from the biblical data, and are meant to safeguard the biblical teaching about God. Everywhere in Scripture, Old Testament and New, we read of only one God who must be worshipped exclusively; and yet, in the New Testament, we're taught that the Father, Son, and Holy Spirit are each God. The Son, the text tells us, prays to the Father and sends the Holy Spirit, which rules out the modalistic understanding of the being of God. Drawing from scripture, then, we know that God is triune: one being and three persons—Father, Son, and Holy Spirit—coequal and coeternal.
Trinity is Greater
Because the Christian God is triune, he is greater the so-called gods of other religions. He is, for instance, loving by nature, something a single-person god cannot be. Before creation, the persons of the Trinity loved each other, while a single-person god cannot love unless he creates something to love. To love, a single-person god needs his creation. The Trinity, on the other hand, is eternally loving and needs nothing in order to love. Love flows out naturally from the Christian God, who can, then, be the source of all love. "Love is from God" (1 John 4:7) will only be true of the Trinity.
It's the Triune God who can save us completely in a way no other god could. The Father chooses and sends and adopts; the Son comes and redeems and intercedes; the Spirit applies and creates and keeps. Our whole Christian life depends on our three-person God.
There is so much more to be said about the beauty of the Trinity. A blog post on the doctrine of the Trinity is a bit like serving up a few crumbs from a lavish cake. Do you want more? Here are a few ways to learn more about our Triune God:
- Read the chapter on the Trinity in your favorite systematic theology. Wayne Grudem's Systematic Theology: An Introduction to Biblical Doctrine is fairly easy to read and understand.
- Read Romans 8:26ff and make a list of everything it tells us about the Father, Son, and Holy Spirit. To get you started: the Spirit helps us in our weakness in verse 26; the Father searches hearts in verse 27; and the Son is the image to which the believer is being conformed in verse 29.
- Do the same thing with Ephesians 1:3-14.
- Study Tim Challies' infographic on the Trinity.
- Read a whole book on the Trinity. I recommend James White's The Forgotten Trinity and Michael Reeve's Delighting in the Trinity: An Introduction to the Christian Faith (If you have other book suggestions, leave them in the comments.) Update 1 : On Twitter, Luma Simms recommended The Deep Things of God: How the Trinity Changes Everything by Fred Sanders. Update 2: I just remembered an excellent book for young children: Big Thoughts For Little Thinkers: The Trinity.