In this short series of articles, we have been thinking about the doctrine of the Trinity. For many ordinary Christians, this doctrine is difficult. How can we make sense of it? And anyway, of what use is it? These are perfectly reasonable concerns, and we need to consider them.
Let’s begin with the problem of analogies. Educators know how important a good illustration or analogy can be in helping to make a difficult point. Here’s a one-liner by journalist Sydney J. Harris, which I came across years ago when trying to work out how best to instill the basics of Christian theology in my students. Students, Harris suggested, “are more like oysters than sausages. The job of teaching is not to stuff them and then seal them up, but to help them open and reveal the riches within.” My own experience as a professor suggests that this isn’t entirely true, but the visual image presents us with a memorable way of understanding an idea.
When finite minds encounter an infinite reality, they struggle to express what they encounter. Using analogies is one way of coping with this. John Calvin is one of many theologians who emphasized how God “adapts to” or “accommodates” our limited capabilities—for example, in using images such as a shepherd to convey truth.
So what analogies could we use for the Trinity? Immediately, we hit a problem. No analogy for God is good enough. I come from Ireland, where the famous missionary Patrick used a shamrock—one of the country’s most familiar native plants—as an analogy for the Trinity. Patrick saw its single leaf with three parts as a way to illustrate one God in three persons.
The doctrine of the Trinity is a reminder of the majesty and mystery of the one who gave Himself on the cross for His people.
Like all analogies, the one I use in my own preaching has weaknesses, but nevertheless it helps make the point. I tell my congregation that we can think of three great roles in the drama of salvation: creation, redemption, and final consummation. Some religions see each of these roles as being played by different agents. For example, some forms of Gnosticism spoke of two quite different gods—a creator god and a redeemer god.
The Christian faith affirms that there is only one God, and that this great and wondrous God creates the world, redeems us, and finally brings things to a glorious end. There may be three roles, but they are all played by the same actor. We can, as John Calvin pointed out, distinguish them, but we cannot separate them.
When using this analogy, I emphasize that there is more to the Trinity than this. After all, if pressed too far, this illustration could lead to “modalism,” the idea that God appears or acts in different ways at different points in history. But it makes a critically important point—that the doctrine of the Trinity enables us to grasp the grandeur and majesty of God by insisting that we do justice to Him.
The doctrine of the Trinity invites us to expand our vision of God rather than reduce it to what we can cope with. We begin by reflecting on the great works of God in creation, then move on to ponder the wonderful work of God in redemption, before finally appreciating the presence of God with us now and in the future.
Perhaps I was a little unkind to Patrick earlier. Let me now hasten to make amends! He’s traditionally regarded as the author of a great Trinitarian hymn, often referred to as “St. Patrick’s Breastplate.” This powerful and deeply evocative hymn reminds the believer how rich the Christian understanding of God is—and that it is this God who has been bonded to the believer through faith. Exulting in the “strong name of the Trinity,” the hymn reinforces this faith by unpacking the presence and power of God in creation, redemption, and consummation.
Right from the beginning, Christians were convinced that in Jesus, they had experienced God’s saving self-revelation. And if Jesus reveals God, He must somehow be said to share in God’s divinity. Otherwise, you wouldn’t really have met God in Christ, and God would remain unknown. If that were the case, God might stand behind Jesus, but wouldn’t be shown or known in and through Him. The doctrine of the Trinity was formulated as a way of safeguarding these basic convictions about salvation and revelation—precious truths that can be easily lost or seen as disconnected ideas. The doctrine of the Trinity weaves these threads together and helps us grasp the “big picture” of God that is revealed in the Bible and confirmed in our experience of prayer and worship.
The doctrine of the Trinity, then, sums up Christian believers’ astonishingly rich and hard-won insights into the nature of God. For the theologian, it is a safeguard against inadequate understandings of God; for the believer, it is a reminder of the majesty and mystery of the one who gave Himself on the cross for His people. It does not really help us to understand God but enables us to avoid inadequate ways of thinking about Him. Faced with the choice between an invented God who could be understood without the slightest difficulty and the real God who couldn’t, the church rightly chose the latter.
Many Christians will still find it easier to talk about God than the Trinity, and they need not be criticized for doing so. But when we begin to reflect on who the one we worship and adore really is, our thoughts move towards a Trinitarian vision of Him. It is here that the long process of thinking about God comes to a stop, as we realize that we can take it no further. And it is here that thought gives way to worship and adoration, captured so well in Reginald Heber’s great hymn:
Holy, holy, holy!
Lord God Almighty!
All Thy works shall praise Thy name,
in earth and sky and sea;
Holy, holy, holy!
Merciful and mighty!
God in three Persons,
This concludes Alister McGrath's three-part series on the Trinity.