Knowing the Trinity

What difference does the doctrine of the Trinity make in our lives? Today, Sinclair Ferguson begins to unfold the significance of knowing God as Father, Son, and Holy Spirit.

Welcome to another week of Things Unseen. This week, I want to think with you about the Trinity. I’ve sometimes said I suspect many Christians think that the doctrine of the Trinity is the most obscure and probably the most speculative doctrine, and therefore, the least practical of all the major Christian doctrines. I remember reading a comment by the Roman Catholic theologian Karl Rahner, about Roman Catholics actually, and wondering if the same was true of Protestants. He wrote that if God were not Trinity, as far as most Christians were concerned, it wouldn’t actually make any difference to their lives.

Three in one and one in three—that doesn’t compute in the mathematics that most of us use, and we tend to operate, I think, on the theological principle that if we don’t understand something, it can’t be all that important. But most of us don’t ever stop to think that if that was our life principle, we wouldn’t be using our computers, our cell phones; we wouldn’t be flying in airplanes. Most of us wouldn’t use electricity, or a hundred other things that we do daily. The fact that we may not fully understand the Trinity doesn’t mean that the Trinity isn’t essential to us.

Perhaps it’s worth pausing to ask this question: Has the fact that God is Trinity crossed your mind this last week or the week before? And if so, has it made any difference to the way you think and live? Many of us would almost die to defend the doctrine of the Trinity. But the question here is, Does the doctrine of the Trinity really make any practical difference to us?

Well, first of all, what are we talking about when we speak about the Trinity? We’re not claiming we fully understand the Trinity. The Bible makes it clear that we would actually need to be the Trinity to understand the Trinity. But here’s what we mean. We mean there is only one God, and this one God exists eternally in a unity of three persons: the Father, the Son, and the Holy Spirit, each of these persons having a distinct relationship to the other two. And we also believe that this is only gradually revealed to us in Scripture, but fully revealed to us in the person of the Lord Jesus Christ.

B.B. Warfield, the great twentieth-century American theologian, uses, I think, a helpful illustration here. He says, “The Old Testament may be likened to a chamber richly furnished but dimly lighted; the introduction of light brings into it nothing which was not in it before; but it brings out into clearer view much of what is in it but was only dimly or not at all perceived before.”

The mystery of the Trinity is not revealed in the Old Testament, but the mystery of the Trinity underlies the Old Testament revelation and here and there almost comes into view. Thus, the Old Testament revelation is not corrected by the fuller revelation which follows, but is only perfected, extended, and enlarged. That fits the opening words of the letter to the Hebrews, doesn’t it? God revealed himself in gradual, partial ways in the Old Testament, but now is revealed Himself by Himself, in Himself in the incarnation of the Son, our Lord Jesus Christ.

And this is a wonderful thing for us to understand. We can describe the Trinity and yet we recognize the Trinity remains a mystery to us. We can know that God is Trinity and know God the Trinity, but we know we can’t fully comprehend Him. After all, even seraphim veil their faces in the presence of the One who is holy, holy, holy.

I remember when our children were young, going to say goodnight to one of our sons. He was sitting up in bed looking a bit puzzled. “Dad,” he said, “is this right that God is three persons in one?” “That’s right,” I replied. To which he said, with the trusting innocence of a five-year-old, “Dad, that’s a very difficult thing for a wee boy like me to understand.” Of course I told him, “It doesn’t get any easier when you get older.”

But that’s the point, isn’t it? God’s trinitarian nature reminds us that while we can know Him, we do not, cannot, and never will, fully comprehend Him, because He is God and we are not. We are finite, created beings. He is the infinite, uncreated One. In seeking, then, to know Him, we mustn’t at the same time fall into the error of reducing Him to our own size. How foolish we would be to think that we are wise when we insist that we would believe in God only if we understood Him. Who do we think we are?

So, there’s something humbling about the doctrine of the Trinity, but there’s also something wonderful. I think I can put it this way: if you think about it, only a three-personed God can fully experience, in eternity, what it really means to love. Otherwise, He’s dependent on creating us. Think about that today because we’re going to return to it again tomorrow.