What is the ‘Trinity’?

The dogma of the Holy Trinity is the greatest mystery of Christian teaching. We know something about it only because God has revealed it through the Incarnation of the Son and the sending of the Holy Spirit. The work of the early Church was largely devoted to refuting Trinitarian heresies, and this mystery remains so inaccessible to our human reason, that it is difficult to talk about it even today without unwittingly positing something potentially heretical.

Though the human mind can never comprehend it, we can come closer to an understanding through the language the Church has developed over the centuries. The Catechism of the Catholic Church points out the three realities about the Trinity which are easily misunderstood:

1. The Trinity is One. We believe not in three gods, but in one God in three persons: “The divine persons do not share the one divinity among themselves but each of them is God whole and entire” (253).
2. The divine persons of the Trinity are truly distinct from one another. “’Father,’ ‘Son,’ and ‘Holy Spirit’ are not simply names designating modalities of the divine being, for they are really distinct from one another … they are distinct from one another in relations of origin: It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds” (254).
3. The distinction of persons in the Trinity “resides solely in the relationships which relate them to one another … While they are called three persons in view of their relations, we believe in one nature or substance … the Father is wholly in the Son and wholly in the Holy Spirit; the Son is wholly in the Father and wholly in the Holy Spirit; the Holy Spirit is wholly in the Father and wholly in the Son” (255).

Through Baptism, every Christian is called to share in the life of the Blessed Trinity, “in the name of the Father and of the Son and of the Holy Spirit.” We share this life in the darkness of faith in this life and in eternal light in the next.