Credo in unum Deum: how contemporary Trinity Sunday proper prefaces obscure monotheism
in the unity of this Godhead there be three Persons, of one substance, power, and eternity.
Or, as the Athanasian Creed declares:
Neither confounding the Persons: nor dividing the Substance.
Key to this, of course, is that the language of 'Persons' is inextricably related to 'Substance'. This is what is seen in the 1662 proper preface for Trinity Sunday:
Who art one God, one Lord; not one only Person, but three Persons in one Substance. For that which we believe of the glory of the Father, the same we believe of the Son, and of the Holy Ghost, without any difference or inequality.
Who, with thine only-begotten Son, and the Holy Ghost, art one God, one Lord, in Trinity of Persons and in Unity of Substance. For that which we believe of thy glory, O Father, the same we believe of the Son, and of the Holy Ghost, without any difference of inequality.
Proper prefaces for Trinity Sunday in contemporary Anglican liturgies, by contrast, abandon 'Substance' while retaining 'Person'. Consider, for example, the Common Worship preface:
And now we give you thanks because you have revealed the glory of your eternal fellowship of love with your Son and with the Holy Spirit, three persons equal in majesty, undivided in splendour, yet one God, ever to be worshipped and adored.
Canada's Book of Alternative Services is similar:
you reveal your glory as the glory of your Son and the Holy Spirit: three persons equal in majesty, undivided in splendour, yet one Lord, one God, ever to be adored in your everlasting glory.
As is Ireland's BCP 2004:
you have revealed your glory as the glory of your Son and of the Holy Spirit: three persons equal in majesty, undivided in splendour, yet one Lord, one God, ever to be worshipped and adored.
Each of these Trinity Sunday proper prefaces, by abandoning 'Substance' while yet retaining 'Persons', obscures the Church's Trinitarian confession, introducing an element of incoherence. The result is an unbalanced rendering of the confession. Crucially, "undivided in splendour" does not and cannot carry the weight of meaning the confession has understood in "one Substance" or "Unity of Substance". (It is worth noting that while the 1662 collect for Trinity Sunday does not use "Substance" neither does it use "Persons": it refers to "Trinity" and "Unity".)
The language of "one Substance" balances "three Persons", ensuring that Church's praise and prayer is rooted in the concern of the Trinitarian confession to worship "one God in Trinity, and Trinity in Unity". It is "one Substance" that signals the fulness and reality of the Unity. Without "one Substance", the Church's praise and prayer is not rightly oriented towards "one Lord, one God". There is an absence of a grounding for this, with no meaningful linguistic sign confirming that the Three Persons are One God.
What is at work here is not merely lazy liturgical revision. The abandonment of the language of "one Substance" and "Unity of Substance" reflects a theological trend, a move away from the classical theism which was essential to securing orthodox the Trinitarian confession towards something radically different. In his Only God Will Save Us: The Nature of God and the Christian Life (2020), Simon Cuff points to the influence of Moltmann:
Moltmann often distinguishes between monotheism and Trinitarianism in such a way as to suggest that Trinitarianism implies a kind of tritheism and doesn't also entail the fundamental unity of God.
He quotes Richard Muller's critique of the "rise in social trinitarianism", in which "oneness is merely social". Mindful that the language of "one Substance" is intimately related to the classical affirmation of divine simplicity, Cuff goes on to say that "divine simplicity may therefore by a safeguard against the potential of tritheism".
There is, then, more than a whiff of social trinitarianism's tritheism in the Trinity Sunday proper prefaces of some contemporary Anglican liturgies, with "three persons" celebrated apart from the "Unity of Substance" fundamental to the Church's Trinitarian confession. One notable exception to this is the proper preface provided in TEC 1979:
For with your co-eternal Son and Holy Spirit, you are one God, one Lord, in Trinity of Persons and in Unity of Being; and we celebrate the one and equal glory of you, O Father, and of the Son, and of the Holy Spirit.
We might, of course, wonder if "Being" - both here and in the Nicene Creed - is a good substitute for "Substance", but it is certainly preferable to an absence of reference to the nature of the Unity that is the Holy Trinity (and the fact that "Being" is capitalised is also not without significance). The TEC 1979 Trinity Sunday proper preface, however, only confirms that there is an issue with the Trinity prefaces offered in a variety of contemporary Anglican liturgies. A fine contemporary alternative, expressing the balance of the classical Trinitarian doctrine, was available in TEC 1979, but it was rejected by liturgical revisions elsewhere in favour of other compositions which abandon the key doctrinal balance of "in Trinity of Persons and in Unity of Substance".
The result is a failure in the Church's praise and prayer on the feast of Trinity to rightly, appropriately, and meaningfully render a fundamental truth of the Faith: Credo in unum Deum. "And the Catholick Faith is this: That we worship one God in Trinity, and Trinity in Unity."
This also has significance for the Church's public witness. Without the confession of "one Substance", Trinity Sunday proper prefaces too easily become an expression of social trinitarianism's cosy embrace of 'community', what Karen Kilby has described as "the individual author's or the larger society's latest ideals of how human beings should live in community". By contrast, the proclamation of the Trinity as "one Substance", as "Unity of Substance", points to the profound truth that humanity stands before the God who is not an ideal egalitarian community to encourage us, but who is the One who alone can save us. As Kilby states:
An emphasis on the unity of God, on the oneness of a God who stands apart from, over-against the world, could arguably be used to undermine as well as to legitimate hierarchical and absolutist forms of government. Before the one God who transcends the world, it might be said, for instance, all human beings are levelled: all alike are creatures, absolutely different from their creator, and any attempt by some to lord it over the others can be seen as a sinful attempt to usurp the place of God.