The Trinity and Us
Does any of this make a difference to my life?
Main teaching: De fide
The big question
The doctrine of the Trinity can seem like a technical puzzle for theologians, with no effect on how anyone prays or lives. Would anything change in a Christian’s life if God were simply one Person? The Church’s answer is that almost everything would.
What the Church teaches
Everything God does outside himself is done by all three Persons together. The Father, the Son and the Holy Spirit are not three principles of creation but one principle (Florence, Decree for the Jacobites, 1442; DH 1331; CCC 258).
How sure is this? De fide.
The Son and the Holy Spirit are sent into the world. The Son is sent in the Incarnation, the Spirit at Pentecost and into the hearts of believers. These missions make known in time the eternal processions (CCC 258, 689–690).
The Trinity dwells in those who are in a state of grace. The Christian is called to share the life of the Trinity now, by grace, and for ever in glory (CCC 260).
How sure is this? The missions are de fide, as Scripture’s own teaching. The indwelling of the Trinity in the just soul is certain: the common teaching of the Fathers and theologians, taught by the Church (CCC 260; Leo XIII, Divinum Illud Munus, 1897).
Where it comes from
Scripture. St Paul sums up the missions in two sentences: “when the time had fully come, God sent forth his Son, born of woman”, and “because you are sons, God has sent the Spirit of his Son into our hearts, crying, ‘Abba! Father!’” (Galatians 4:4–6). Through the Son, he writes elsewhere, “we both have access in one Spirit to the Father” (Ephesians 2:18).
Jesus promises the indwelling: “If a man loves me, he will keep my word, and my Father will love him, and we will come to him and make our home with him” (John 14:23). Paul reminds Christians that “your body is a temple of the Holy Spirit within you” (1 Corinthians 6:19), and St Peter speaks of becoming “partakers of the divine nature” (2 Peter 1:4).
The early Church and the saints. St Augustine, looking back on the years before his conversion, wrote to God that he had been searching outside himself while God was more inward to him than his own inmost self (Confessions 3.6.11). The Fathers taught that the purpose of the whole economy of salvation is that we should come to share the life of the Trinity (CCC 260).
How theologians explain it
One action, three Persons. God acts outside himself through his nature and power, and the three Persons share one nature. So when God creates, redeems or sanctifies, all three act. Creation is the work of the Father, through the Son, in the Spirit: one act, not three.
Appropriation. Yet Scripture and the liturgy often connect particular works with particular Persons: creation with the Father, redemption with the Son, sanctification with the Spirit. Theologians call this appropriation. Some work is “appropriated” to a Person because it resembles what is proper to that Person: power to the Father, the source; wisdom to the Son, the Word; love and holiness to the Spirit, the Love of the Father and the Son. This helps us see each Person more clearly, without dividing their work (Summa I, q. 39, aa. 7–8).
Missions: the Trinity turned toward us. A divine Person is “sent” when he begins to be present in a new way in creation. The sending reveals where he comes from:
| Eternal procession | Mission in time | |
|---|---|---|
| Son | Begotten of the Father | Sent by the Father: the Incarnation |
| Holy Spirit | Breathed forth by the Father and the Son | Sent by the Father and the Son: Pentecost, and into every soul in grace |
| Father | From no one | Never sent, but comes with the others to dwell in the soul |
Aquinas distinguishes visible missions, such as the Incarnation, or the Spirit appearing as a dove or tongues of fire, from invisible missions, when the Son and Spirit come to dwell in a soul through grace (Summa I, q. 43).
Why the Trinity changes everything. If God were one solitary Person, love would not belong to his very being; he would need a world to love. Because God is Trinity, the Father eternally loves the Son in the Spirit, so “God is love” (1 John 4:8) is true of God in himself. And Christian life has a Trinitarian shape:
- Baptism is in the name of the Father, the Son and the Holy Spirit.
- Prayer is directed to the Father, through the Son, in the Holy Spirit; nearly every prayer of the Mass ends that way.
- Adoption: the Spirit makes us children of the Father in the Son, so that we can call God “Abba” with Jesus (Romans 8:15).
- Heaven is entering fully into the life and love of the three Persons (CCC 260).
Philosophy bridge
The philosophy course’s account of efficient causality explains why the Persons’ outward works are one: an agent acts through its nature and power, and the three Persons have one nature and one power. What is distinct in God, the relations, does not lead to three separate actions in the world.
What the Church does not claim
- Not that the Father alone creates, the Son alone redeems, and the Spirit alone sanctifies. These are appropriations. All three act in every work, though only the Son became man.
- Not that the indwelling makes us God by nature. We become sharers in the divine life by grace, while remaining creatures.
- Not that the Trinity is an abstraction. The Catechism calls it the central mystery of Christian faith and life (CCC 234).
- Not that only experts can understand it enough to live it. Every child who makes the sign of the cross and prays the Our Father is already living within the Trinity.
Check your understanding
- What did the Council of Florence teach about the outward works of the Trinity?
Show answer
That the Father, the Son and the Holy Spirit are not three principles of creation but one principle: all God’s works outside himself are done by all three together.
- What is appropriation? Give an example.
Show answer
Attributing a work common to all three Persons to one Person, because it resembles what is proper to him. For example, creation is appropriated to the Father, the source; sanctification to the Holy Spirit, who is Love.
- What is the difference between a procession and a mission?
Show answer
A procession is a Person’s eternal origin within God. A mission is that Person’s being sent into the world in time, which makes the procession known: the Son in the Incarnation, the Spirit at Pentecost and in grace.
- Which passage of Scripture promises that the Trinity will dwell in those who love God?
Show answer
John 14:23: “my Father will love him, and we will come to him and make our home with him.” Also 1 Corinthians 6:19.
- Give two ways in which ordinary Christian life is shaped by the Trinity.
Show answer
Any two of: baptism in the name of the three Persons; praying to the Father through the Son in the Spirit; being adopted as children of the Father in the Son by the Spirit; the hope of heaven as sharing the life of the Trinity; the sign of the cross.