Today’s Catechism sections deal with the dogma of the Trinity and its formation in the Early Church. The supplemental material comes from Frank Sheed’s classic work, “Theology and Sanity”.


The formation of the Trinitarian dogma

249 From the beginning, the revealed truth of the Holy Trinity has been at the very root of the Church's living faith, principally by means of Baptism. It finds its expression in the rule of baptismal faith, formulated in the preaching, catechesis and prayer of the Church. Such formulations are already found in the apostolic writings, such as this salutation taken up in the Eucharistic liturgy: "The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all."81

250 During the first centuries the Church sought to clarify her Trinitarian faith, both to deepen her own understanding of the faith and to defend it against the errors that were deforming it. This clarification was the work of the early councils, aided by the theological work of the Church Fathers and sustained by the Christian people's sense of the faith.

251 In order to articulate the dogma of the Trinity, the Church had to develop her own terminology with the help of certain notions of philosophical origin: "substance", "person" or "hypostasis", "relation" and so on. In doing this, she did not submit the faith to human wisdom, but gave a new and unprecedented meaning to these terms, which from then on would be used to signify an ineffable mystery, "infinitely beyond all that we can humanly understand".82

252 The Church uses (I) the term "substance" (rendered also at times by "essence" or "nature") to designate the divine being in its unity, (II) the term "person" or "hypostasis" to designate the Father, Son and Holy Spirit in the real distinction among them, and (III) the term "relation" to designate the fact that their distinction lies in the relationship of each to the others.

The dogma of the Holy Trinity

253 The Trinity is One. We do not confess three Gods, but one God in three persons, the "consubstantial Trinity".83 The divine persons do not share the one divinity among themselves but each of them is God whole and entire: "The Father is that which the Son is, the Son that which the Father is, the Father and the Son that which the Holy Spirit is, i.e. by nature one God."84 In the words of the Fourth Lateran Council (1215), "Each of the persons is that supreme reality, viz., the divine substance, essence or nature."85

254 The divine persons are really distinct from one another. "God is one but not solitary."86 "Father", "Son", "Holy Spirit" are not simply names designating modalities of the divine being, for they are really distinct from one another: "He is not the Father who is the Son, nor is the Son he who is the Father, nor is the Holy Spirit he who is the Father or the Son."87 They are distinct from one another in their relations of origin: "It is the Father who generates, the Son who is begotten, and the Holy Spirit who proceeds."88 The divine Unity is Triune.

255 The divine persons are relative to one another. Because it does not divide the divine unity, the real distinction of the persons from one another resides solely in the relationships which relate them to one another: "In the relational names of the persons the Father is related to the Son, the Son to the Father, and the Holy Spirit to both. While they are called three persons in view of their relations, we believe in one nature or substance."89 Indeed "everything (in them) is one where there is no opposition of relationship."90 "Because of that unity 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."91

256 St. Gregory of Nazianzus, also called "the Theologian", entrusts this summary of Trinitarian faith to the catechumens of Constantinople:

Above all guard for me this great deposit of faith for which I live and fight, which I want to take with me as a companion, and which makes me bear all evils and despise all pleasures: I mean the profession of faith in the Father and the Son and the Holy Spirit. I entrust it to you today. By it I am soon going to plunge you into water and raise you up from it. I give it to you as the companion and patron of your whole life. I give you but one divinity and power, existing one in three, and containing the three in a distinct way. Divinity without disparity of substance or nature, without superior degree that raises up or inferior degree that casts down. . . the infinite co-naturality of three infinites. Each person considered in himself is entirely God. . . the three considered together. . . I have not even begun to think of unity when the Trinity bathes me in its splendor. I have not even begun to think of the Trinity when unity grasps me. .92


265 By the grace of Baptism "in the name of the Father and of the Son and of the Holy Spirit", we are called to share in the life of the Blessed Trinity, here on earth in the obscurity of faith, and after death in eternal light (cf. Paul VI, CPG # 9).

266 "Now this is the Catholic faith: We worship one God in the Trinity and the Trinity in unity, without either confusing the persons or dividing the substance; for the person of the Father is one, the Son's is another, the Holy Spirit's another; but the Godhead of the Father, Son and Holy Spirit is one, their glory equal, their majesty coeternal" (Athanasian Creed: DS 75; ND 16).

267 Inseparable in what they are, the divine persons are also inseparable in what they do. But within the single divine operation each shows forth what is proper to him in the Trinity, especially in the divine missions of the Son's Incarnation and the gift of the Holy Spirit.

Perhaps the best description I have found of the mystery of the Trinity is present in “Theology and Sanity” by Frank Sheed. It is a long read, but well worth it for the simplicity with which Sheed explains this tremendously complicated subject (here is a longer excerpt from the book):

(ii) "Person" and "Nature"

Let us come now to a consideration of the doctrine of the Blessed Trinity to see what light there is in it for us, being utterly confident that had there been no light for us, God would not have revealed it to us. There would be a rather horrible note of mockery in telling us something of which we can make nothing. The doctrine may be set out in four statements:

In the one divine Nature, there are three Persons - the Father, the Son, and the Holy Spirit.

The Father is not the Son, the Son is not the Holy Spirit, the Holy Spirit is not the Father: no one of the Persons is either of the others.

The Father is God, the Son is God, the Holy Spirit is God.

There are not three Gods but one God.

We have seen that the imagination cannot help here. Comparisons drawn from the material universe are a hindrance and no help. Once one has taken hold of this doctrine, it is natural enough to want to utter it in simile and metaphor - like the lovely lumen de lumine, light from light, with which the Nicene Creed phrases the relation of the Son to the Father. But this is for afterward, poetical statement of a truth known, not the way to its knowledge. For that, the intellect must go on alone. And for the intellect, the way into the mystery lies, as we have already suggested, in the meaning of the words "person" and "nature". There is no question of arithmetic involved. We are not saying three persons in one person, or three natures in one nature; we are saying three persons in one nature. There is not even the appearance of an arithmetical problem. It is for us to see what person is and what nature is, and then to consider what meaning there can be in a nature totally possessed by three distinct persons.

The newcomer to this sort of thinking must be prepared to work hard here. It is a decisive stage of our advance into theology to get some grasp of the meaning of nature and the meaning of person. Fortunately the first stage of our search goes easily enough. We begin with ourselves. Such a phrase as "my nature" suggests that there is a person, I, who possesses a nature. The person could not exist without his nature, but there is some distinction all the same; for it is the person who possesses the nature and not the other way round.

One distinction we see instantly. Nature answers the question what we are; person answers the question who we are. Every being has a nature; of every being we may properly ask, What is it? But not every being is a person: only rational beings are persons. We could not properly ask of a stone or a potato or an oyster, Who is it?
By our nature, then, we are what we are. It follows that by our nature we do what we do: for every being acts according to what it is. Applying this to ourselves, we come upon another distinction between person and nature. We find that there are many things, countless things, we can do. We can laugh and cry and walk and talk and sleep and think and love. All these and other things we can do because as human beings we have a nature which makes them possible. A snake could do only one of them - sleep. A stone could do none of them. Nature, then, is to be seen not only as what we are but as the source of what we can do.

But although my nature is the source of all my actions, although my nature decides what kind of operations are possible for me, it is not my nature that does them: I do them, I the person. Thus both person and nature may be considered sources of action, but in a different sense. The person is that which does the actions, the nature is that by virtue of which the actions are done, or, better, that from which the actions are drawn. We can express the distinction in all sorts of ways. We can say that it is our nature to do certain things, but that we do them. We can say that we operate in or according to our nature. In this light we see why the philosophers speak of a person as the center of attribution in a rational nature: whatever is done in a rational nature or suffered in a rational nature or any way experienced in a rational nature is done or suffered or experienced by the person whose nature it is.

Thus there is a reality in us by which we are what we are: and there is a reality in us by which we are who we are. But as to whether these are two really distinct realities, or two levels of one reality, or related in some other way, we cannot see deep enough into ourselves to know with any sureness. There is an obvious difference between beings of whom you can say only what they are and the higher beings of whom you can say who they are as well. But in these latter - even in ourselves, of whom we have a great deal of experience - we see only darkly as to the distinction between the what and the who. Of our nature in its root reality we have only a shadowy notion, and of our self a notion more shadowy still. If someone - for want of something better to say - says: "Tell me about yourself", we can tell her the qualities we have or the things we have done; but of the self that has the qualities and has done the things, we cannot tell her anything. We cannot bring it under her gaze. Indeed we cannot easily or continuously bring it under our own. As we turn our mind inward to look at the thing we call "I", we know that there is something there, but we cannot get it into any focus: it does not submit to being looked at very closely. Both as to the nature that we ourselves have and the person that we ourselves are, we are more in darkness than in light. But at least we have certain things clear: nature says what we are, person says who we are. Nature is the source of our operations, person does them.

Now at first sight it might seem that this examination of the meaning of person and nature has not got us far toward an understanding of the Blessed Trinity. For although we have been led to see a distinction between person and nature in us, it seems clearer than ever that one nature can be possessed and operated in only by one person. By a tremendous stretch, we can just barely glimpse the possibility of one person having more than one nature, opening up to him more than one field of operation. But the intellect feels baffled at the reverse concept of one nature being totally "wielded", much less totally possessed, by more than one person. Now to admit ourselves baffled by the notion of three persons in the one nature of God is an entirely honorable admission of our own limitation; but to argue that because in man the relation of one nature to one person is invariable, therefore the same must be the relation in God, is a defect in our thinking. It is indeed an example of that anthropomorphism, the tendency to make God in the image of man, which we have already seen hurled in accusation at the Christian belief in God.


81 ⇒ 2 Cor 13:14; cf. ⇒ I Cor 12:4 - 6; ⇒ Eph 4:4-6.
82 Paul VI, CPC # 2.
83 Council of Constantinople II (553): DS 421.
84 Council of Toledo XI (675): DS 530:26.
85 Lateran Council IV (1215): DS 804.
86 Fides Damasi: DS 71.
87 Council of Toledo XI (675): DS 530:25.
88 Lateran Council IV (1215): DS 804.
89 Council of Toledo XI (675): DS 528.
90 Council of Florence (1442): DS 1330.
91 Council of Florence (1442): DS 1331.
92 St. Gregory of Nazianzus, Oratio 40, 41: PG 36,417.