In a work on the sacraments in Roman Catholic theology, Dom Wulstan Mork admitted that the concept of a Tri-une God was unknown until the coming of Christ:
The whole Old Testament is emphatic on this one point: God is not merely a force, an energy, but a person. (There is no revelation of the existence of three persons in God until Christ’s coming.) . . . But Christ revealed that God is one in three Persons, a Trinity. This is a strict mystery that the intellect alone could never discover, nor even now can it understand. (Dom Wulstan Mork, Transformed by Grace: Scripture, Sacraments and the Sonship of Christ [Cincinnati, Ohio: Servant Books, 1965, 2004], 9, 29)
Elsewhere, he offered the following on Confirmation; I have been thinking about this topic recently as I am speaking at a baptism tomorrow and will be participating in the confirmation on Sunday:
Confirmation gives the fullness of the Holy Spirit, therefore the fullness of sonship. This is the essence of the sacrament, its meaning and its purpose.
It is true that we received the Holy Spirit in baptism, we “were all given to drink of a single Spirit.” What more is there to receive? What is this “fullness”? The reason for confirmation is that the Holy Spirit “anointed” Christ on two occasions: at the Incarnation, when he united the human nature to the Son; and after Christ’s baptism, when he descended upon him in the form of a dove. Our baptism was our first anointing by the Spirit, our Incarnation. Because the Son received a second, so must we adopted sons. “Confirmation extends to us the mystery of the baptism of Christ in the Jordan when the Father publicly proclaimed him Son at the inauguration of his messianic mission.” (Ibid., 135)