Home / Articles / Sermons / The Doctrine Of The Holy Trinity – A Brief Explanation

The Doctrine Of The Holy Trinity – A Brief Explanation

(By Fr. Dexter Brereton)

Amazon ImageThe Gospel reading taken from the final passages of Matthew’s gospel reflect a Trinitarian baptismal formula that was already in use by the time Matthew set these words into writing: “baptise them in the name of the Father and of the Son and of the Holy Spirit.” These words stand at the centre of today’s celebration of the Most Holy Trinity.

The liturgical year of the Catholic Church contains two kinds of feast (major celebrations ). The first and most frequent kind of celebration is known as a “mystery” feast or a “story” feast. This kind of feast commemorates saving events in the history of salvation e.g. Christmas (birth of Our Lord), Easter (the resurrection of Jesus). The other kind of celebration is known as an “idea” feast. An idea feasts celebrates important notions, or concepts or ideas in the Christian faith. Well today’s feast, the Solemnity of the Most Holy Trinity is such a feast. It is an idea feast. We celebrate the central belief of our Church which is expressed in what we call the “Doctrine of the Holy Trinity.” This doctrine is the answer to a question: “When you say God…what do you mean?” We say: “Based our experience of God and that of those who have gone before us, we affirm with Israel that there is only ONE GOD. This God is a Trinity of persons, Father, Son and Holy Spirit; each person distinct from the other two: the Father is not the Son nor is the Father the Holy Spirit, the Son is neither Father nor Spirit and the Spirit is neither Father nor is the Spirit the Son, yet this God remains one.”

The doctrine of the Trinity then is a summary statement of Christian faith and experience.

In fact in Christian Tradition there are three primary sources of our Trinitarian faith:

  1. The historical experience of salvation recording in sacred scripture and re-interpreted down through the ages.
  2. The testimony of public worship
  3. The experience of practicing discipleship today.

In the celebration of the sacred liturgy, it is the witness of scripture which takes pride of place as we celebrate our faith in the God who is both one and three.  Reflecting on the revelation of God in scripture St. Gregory of Nazianzus wrote:

The old covenant made clear proclamation of the Father

a less definite one of the Son. The new covenant made the Son manifest

and gave us a glimpse of the Spirit’s Godhead.

…No, God meant it be by piecemeal additions, “ascents” as David

called them, by progress and advance from glory to glory, that

the light of the Trinity should shine upon more illustrious souls.

One gets here this sense that in the long story of salvation in the bible, the God that we worship and love is revealed to our understanding in “stages” in “leaps” or in “ascents” as Gregory says. God put Israel through a long apprenticeship of miracles, deliverance and hardship. Bit by bit Israel came to trust God as “Father” not so much of an individual but of the whole nation. God is Israel’s Father because God gave them birth (Deuteronomy 32: 18) by electing and adopting them as  his own people. Other experiences going right down to the time of Jesus revealed God to be the Son who is the Word who was “with God, and the Word was God (John 1: 1).” Then Jesus himself would call the Spirit “the Spirit of truth which comes from the Father (John 15:26).” He “leads us into the complete truth.” (John 16: 13).

Today disciples can discover the Trinity not simply by careful reading of scripture and by study but from the inside, by reflecting on our own deep experiences when God touches us. Today’s gospel reading from Matthew 28 shows Jesus in a moment of clarity and insight. He has risen from the dead and all is clear to him. He knows that he is blessed with God’s “authority” and now speaks to his disciples one last time “in the place of God” using God’s authority.

People who have successfully come through some kind of difficult experience, have this sense of “speaking” with God’s authority. This is what it means to be “Son”. Your life experience, your insight is nothing less than “God’s wisdom.” No human being taught this too you. You are speaking the very words of God. A divorced woman helping other abused women free themselves can say “all authority on heaven and earth has been given to me.” This is not some authority she got from a book or doing a course, it is authority from God, from the “school of life.” She knows in her wisdom she speaks God’s words. The same for a former drug addict helping other addicts, or an activist working for unity in the community. All these, like Jesus enjoy this moment of clarity when like Jesus they can say “all authority in heaven and on earth has been given to me.”


Lord we thank you for our experiences like Jesus when we realize that we are speaking “in your place” speaking with “your authority” to others. Help us then to trust that at the end of the day it is your power which guides us and everything that we do.


Shop for thousands of Catholic gifts at Aquinas and More