During class the other night, I was trying to reconstruct from memory the comments made by J. I. Packer in an interview I’d read earlier in the week.
The interview is no longer available on the web, but here is part of what Packer said about trying to explain the Trinity. His comments are both helpful and thought-provoking:
If the approach I’m trying to spell out is right, then the question doesn’t need to be put quite that way. It’s certainly true that all the classic illustrations of the Trinity break down. You only have to look at them twice to realize that. The Trinity is not like water, which at different temperatures can be liquid, solid, or steam. The Trinity is not like a cloverleaf, where you have the three little leaves making one big leaf. The Trinity is not like a cube, which has a number of sides but nonetheless is one cube.
What’s so bad about all those illustrations is they lose sight, from the word go, of the truth that the Trinity is three persons — persons who are more personal than we are, persons whose personhood ought to be highlighted and shouted from the housetops. Neither the Father nor the Son nor the Holy Spirit is inanimate or a thing. Each of the three is he.
You have to say “he” because that conveys to people’s minds straightaway the image of a stronger Person than the word she would do. It isn’t that you’re giving sex to either the Father, the Son, or the Holy Spirit either way. It’s that you’re using the strongest personal pronoun that you’ve got to express the thought that here is the strongest personhood that we’ve ever confronted, stronger and fuller and more thrustful than your personhood or my personhood or anybody’s personhood. We talk about strong personalities. Well, the Father, the Son, and the Holy Spirit are way stronger than any of our human strong personalities. God is the Creator, after all.
If we have to use a formula, the best formula is that he — that’s God — is they; and they — that’s the Father, Son, and Holy Spirit — are he. Three persons, one God. But you’re highlighting the fact that we are talking about persons. Because the illustrations don’t catch any of that, I would say throw them away.
I’ve often been asked: What then do you teach kids in Sunday school? (Which is where these illustrations are commonly used.) And I say, when they can begin to understand this at age two or three, start telling them about three friends who, in a wonderful way they can’t understand — and Dad and Mom can’t understand and nobody can understand, yet it’s true — are one Being. Teach them to think of what the Father does for us. Teach them to think of the Lord Jesus as the friend who sticks closer than a brother — the friend who has saved you and is saving you, taking you along the path that leads to a heavenly home. And teach them to think about the Holy Spirit, the helper inside. Here they are: your three friends, your one God.
I think children can understand that. They know what it’s like to have a person coming alongside to help them and serve them and lead them and direct them in one way or another. And if people teach that way, the need for unhelpful illustrations simply dissolves away, and you don’t at any point need to run into abstractions. In fact, talking about the three friends means turning your back on abstractions just as it’s turning your back on impersonal illustrations. So to answer the latter part of your question, abstraction doesn’t enter into it. It’s the doctrine of the three heavenly friends.