The Collect for Trinity Sunday
Almighty and everlasting God, you have given to us your servants grace, by the confession of a true faith, to acknowledge the glory of the eternal Trinity, and in the power of your divine Majesty to worship the Unity: Keep us steadfast in this faith and worship, and bring us at last to see you in your one and eternal glory, O Father; who with the Son and the Holy Spirit live and reign, one God, for ever and ever. Amen.
Trinity Sunday: Some History
The Sunday after Pentecost Sunday has been known and celebrated as “Trinity” Sunday for quite some time. According to The Episcopal Church’s very helpful “Episcopal Dictionary of the Church,”
Celebration of Trinity Sunday was approved for the western church by Pope John XXII in 1334. This feast is associated with Thomas Becket (c. 1118-1170), who was consecrated bishop on Trinity Sunday, 1162. His martyrdom may have influenced the popularity of the feast in England and the custom of naming the remaining Sundays of the church year “Sundays after Trinity.” The Sarum Missal and editions of the Prayer Book through the 1928 BCP named these Sundays the Sundays after Trinity. The 1979 BCP identifies this portion of the church year as the season after Pentecost, and names these Sundays the Sundays after Pentecost (see  BCP, p. 32).
The Doctrine of the Trinity
As its name suggests, Trinity Sunday is a time to focus on the Christian doctrine of the Trinity, the teaching that there is one God in three Persons—Father, Son, and Holy Spirit.
Here’s how that doctrine is stated in the first of the Thirty-Nine Articles of Religion:
There is but one living and true God, everlasting, without body, parts, or passions; of infinite power, wisdom, and goodness; the Maker, and Preserver of all things both visible and invisible. And in unity of this Godhead there be three Persons, of one substance, power, and eternity; the Father, the Son, and the Holy Ghost.
For a much more elaborate statement of the doctrine of the Trinity, consider the words of the Athanasian Creed:
And the catholic faith is this: That we worship one God in Trinity, and Trinity in Unity;
Neither confounding the persons nor dividing the substance.
For there is one person of the Father, another of the Son, and another of the Holy Spirit.
But the Godhead of the Father, of the Son, and of the Holy Spirit is all one, the glory equal, the majesty coeternal.
Such as the Father is, such is the Son, and such is the Holy Spirit.
The Father uncreated, the Son uncreated, and the Holy Spirit uncreated.
The Father incomprehensible, the Son incomprehensible, and the Holy Spirit incomprehensible.
The Father eternal, the Son eternal, and the Holy Spirit eternal.
And yet they are not three eternals but one eternal.
As also there are not three uncreated nor three incomprehensible, but one uncreated and one incomprehensible.
So likewise the Father is almighty, the Son almighty, and the Holy Spirit almighty.
And yet they are not three almighties, but one almighty.
So the Father is God, the Son is God, and the Holy Spirit is God;
And yet they are not three Gods, but one God.
So likewise the Father is Lord, the Son Lord, and the Holy Spirit Lord;
And yet they are not three Lords but one Lord.
For like as we are compelled by the Christian verity to acknowledge every Person by himself to be God and Lord;
So are we forbidden by the catholic religion to say; There are three Gods or three Lords.
The Father is made of none, neither created nor begotten.
The Son is of the Father alone; not made nor created, but begotten.
The Holy Spirit is of the Father and of the Son; neither made, nor created, nor begotten, but proceeding.
So there is one Father, not three Fathers; one Son, not three Sons; one Holy Spirit, not three Holy Spirits.
And in this Trinity none is afore or after another; none is greater or less than another.
But the whole three persons are coeternal, and coequal.
So that in all things, as aforesaid, the Unity in Trinity and the Trinity in Unity is to be worshipped.
If you’d like to read my attempts at explaining the doctrine of the Trinity, read “The Holy Trinity: What is it? (Why) is it important?” and “Theology in Outline: What Do I Believe?”.
OK, with the doctrine of the Trinity in mind, let’s consider the collect for Trinity Sunday.
1. The Doctrine of the Trinity is a Gracious Gift of the Triune God, for the Sake of God’s Glory
Almighty and everlasting God, you have given to us your servants grace, by the confession of a true faith, to acknowledge the glory of the eternal Trinity, and in the power of your divine Majesty to worship the Unity:
First, the collect for Trinity Sunday reminds us that the doctrine of the Trinity is itself a gracious gift of the Triune God!
We Christians don’t get to pat ourselves on the back for being clever enough to figure God out. We don’t get to wield the doctrine of the Trinity like a weapon we forged.
Instead, we receive the doctrine of the Trinity as a gift of the Triune God. The Father, the Son, and the Holy Spirit, though they have existed for eternity in perfect communion and fellowship with one another as God, saw fit to extend the divine fellowship to creation. God has graciously revealed himself to us as he truly is—triune.
2. Faithfulness in Faith and Worship is a Gracious Gift of the Triune God, for the Sake of God’s Glory
Keep us steadfast in this faith and worship, and bring us at last to see you in your one and eternal glory, O Father; who with the Son and the Holy Spirit live and reign, one God, for ever and ever. Amen.
Furthermore, we Christians don’t get to pat ourselves on the back for faithfulness to trinitarian orthodoxy. The doctrine of the Trinity isn’t for our glory, it is for God’s, that we might worship God rightly!
This doesn’t mean that trinitarian heresies are not serious. In fact, it makes them very serious! They ought to be opposed with correct teaching.
However, I do believe that this changes how we combat trinitarian errors. We can’t do so from a position of moral superiority. The doctrine of the Trinity is a gracious gift of God. No one “merits” it, neither the most fastidiously orthodox trinitarian theologian nor the most erroneous trinitarian heretic.
This Trinity Sunday, we all pray for the grace to worship God as he truly is and as he has revealed himself to be: One God in Three Persons—Father, Son, and Holy Spirit.
What about the rest of the week?
OK, so, technically, you’re not supposed to use the collect for Trinity Sunday for the weekdays following Trinity Sunday.
Instead, you use the collect from the “Season after Pentecost” (AKA “Season after Trinity,” AKA “Ordinary Time”) which corresponds to the date of Trinity Sunday.
So, this year (2018), we use the following collect for the weekdays after Trinity Sunday.
Week of the Sunday from May 22 to May 28
O Lord, we entreat you mercifully to hear us, and grant that we, to whom you have given the desire to pray, may by your mighty aid be defended and comforted in all our adversities; through Jesus Christ our Lord, who lives and reigns with you and the Holy Spirit, one God, for ever and ever. Amen.
I love this prayer, because it acknowledges that God himself gives us the very desire to pray!
On that basis, the collect requests that God would, in his mercy, hear us when we pray. Specifically, we need God to defend us and comfort us in our adversities here on earth.
According to the logic of this collect, we can trust that God will hear us, defend us, and comfort us because he wants us to pray to him for these things. Otherwise, he would not give us the desire to pray.