Trinity Sunday themes

Year A: The work of the God-head fully vested in creation.
Year B: The work of the God-head fully vested in salvation.
Year C: The work of the God-head fully vested in our lives.

Year A: Too much Power for one Person.
Year B: Too much Holiness for one Person.
Year C: Too much Love for one Person.

Adoration is a good place to start. Holy, Holy, Holy! The Trisagion expresses the completeness of the awesome holiness of God. It serves as a worship litany for the whole vision of the holiness of God. He is too holy for one being. He says, “who will go for us.” He is too much God for one person. In Hebrew thought this should be no offence to call the one God three, he is completely God as he is completely holy.

The Pulpit Commentary states,

“The triple repetition has been understood in all age of the Church as connected
with the doctrine of the Trinity. Holy is he who has created us, and bidden us
to worship him in the beauty of holiness! Holy is he who has redeemed us,
and washed away our sins, and made us by profession holy! Holy is he who
day by day sanctifies us, and makes us in very deed and truth, so far as we will
permit him, holy! The whole earth is full of his glory.”

The palmist sings of the earth full of his glory, shaken by his voice, trembling before his holiness, inviting us to join in ascribing glory to his name!

So then, brothers and sisters, we are debtors, not to the flesh, to live according to the flesh--for if you live according to the flesh, you will die; but if by the Spirit you put to death the deeds of the body, you will live.

Paul’s, “So then,” is as good a response to the glory of the Old-Testament readings as it is to the indwelling of the Spirit who raised Christ from the dead. He provides a nice and essential transition from Pentecost Sunday to Trinity Sunday.
Jesus too puts action to our ascribing Glory to the Lord of Hosts. He begins with the renewing power of the Spirit and continues with the sending and Holy Father, finishing with the sent and sacrificed Son. The whole thrice-Holy, thrice-powerful, thrice-God is involved in our new birth, brining us to a place where we can stand, holy, in the awful presence of God and cry Holy, Holy, Holy!