This was in CWB II so I looked at it there.
The text is by John Henry Cardinal Newman and it is set to Elgar’s DRAKES BROUGHTON. The text below differs from CWB II – the alt was less back then.
I updated my organ backing:
Firmly I believe and truly
God is Three and God is One;
And I next acknowledge duly
Manhood taken by the Son.And I trust and hope most fully
In that manhood crucified;
And each thought and deed unruly
Do to death, as He has died.And I hold in veneration,
For the love of him alone,
Holy Church as His creation,
And her teachings, as his own.Adoration aye be given,
With and through the angelic host,
To the God of earth and heaven,
Father, Son and Holy Ghost.