The doctrine of the Trinity is not only essential for good theology. Getting the Trinity right is also essential for love, politics, and art. God is an absolute union of three distinct persons. Thus, Scripture teaches that “God is love” (1 John 4:16). Not just that He is loving, but that He is, literally, love. That is, a union of distinct persons.
Since God is love, His triune nature can teach us about what real love has to involve. According to the Athanasian Creed, we can err in regards to the Trinity either by “confounding the persons” (that is, smushing them all together into one) or by “dividing the substance” (that is, separating the Father, Son, and Holy Spirit into three deities).
There can be heretics in love, as well as in theology. Some relations make the mistake of “confounding the persons.” A husband wants his wife to be exactly like he is. He wants her to conform exactly to his will. He does not allow her to be a separate person. He says he loves her, but in expecting her to conform to what he is, he is really only loving himself. This is no more love than Unitarianism is Christianity.
Or consider a family, in which the father, mother, and children each exist in their own self-contained worlds and have nothing to do with each other. They don’t have meals together, they don’t communicate with each other, they are content to just be themselves. They are “dividing the substance” of the family. The family members are separate persons, to be sure — and some families fall into the Unitarian heresy — but they lack unity. They think they love each other in their toleration, niceness, and acceptance of the others’ differences. But this is no more love than polytheism is Christianity.
True love — whether for and from a man and a woman, family members, friends, neighbors, or God Himself — affirms the “otherness” of the beloved. And, at the same time, is “one” with the beloved. The two have their own identities, and they also identify with each other, so as to form a unity beyond themselves. This is love by Trinitarian standards.
We can extend this to society as a whole. God Himself is a sort of community, three distinct persons in one essence. That we human beings were created in His image must account for our social nature. It is not good for us to be alone (Gen. 2:18). So He has placed us in families, communities, and nations, making us dependent on others for our very survival. In a Trinitarian society, each member is a separate, individual person who — out of love for his neighbor — joins with the other members into a corporate unity. Families, churches, companies, governments are all societies in which we have both individual and corporate identities.
In this sinful world, of course, such societies often turn heretical. The high school social scene that demands absolute conformity — this would be an example of “confounding the persons,” suppressing the unique individuality of the persons who constitute the group. Another would be a dictatorship that controls its citizens by stamping out liberties.
The opposite heresy would be an assemblage of people in which there is no unity, no admission of common bonds or obligations, in which everyone lives completely for himself. This would be “dividing the persons.”
We can also apply the Trinity to the creation He has made. God made a “universe” of an astounding variety of different things, which cohere into elements, species, and ecosystems. As the Psalmist put it, “O Lord, how manifold are your works!” (Ps. 104:24). Cells, each with their own individuality, come together to form a single organism.
“The body is one and has many members, and all the members of the body, though many, are one body,” says the apostle Paul (1 Cor. 12:12). He uses biological facts about eyes, ears, and feet as an image of theological and moral truth about the organism of the church. These utterly different organs come together — in a Trinitarian way — to form one unified body. Similarly, the utterly diverse Christians — with their different personalities, backgrounds, and gifts — who together constitute nothing less than the body of Christ on earth, should treat each other in a Trinitarian way: honoring each other’s differences, while being completely united in Christ (see vv. 13–25). In the physical body, as in the communion of the saints, “If one member suffers, all suffer together; if one member is honored, all rejoice together” (v. 26).
The unity of variety is also a principle of aesthetics. Some works of art have unity — consider the black canvas of the modern art gallery — but no variety. Others have variety — consider the spattered canvas of the paint-flinging abstract expressionist — but no unity. But the greatest works of art, whether painting or music or literature, have “a lot to them,” filled with details and an abundance of elements interesting in their own terms. And yet — as in the multiple melodies of a Bach fugue or the innumerable characters and subplots of a Shakespeare play — they also all come together into a larger whole.
This fallen world is a realm of heresies, but looming behind all that is true and good and satisfying is the triune God.