What is the Trinity?
The simplest definition of the Trinity is “Three persons in one God” (CCC 253). Definitions are not much help with understanding the trinity as God is impossible to imagine.
So let's start with God the Father. We have already discussed that God is infinite. God the Father, being God is infinite. St John said that “God is Love” (1 John 4:8) and since love is a gift of self, The father is a pure infinite gift of self. God the Father is so giving that he doesn't just give stuff to others, but he gives his very self. This self gift of the Father is so powerful, it is another divine person - The Son. All that the Father is, is given to the Son and is what the Son is. The Son as God receives all that the Father is perfectly. This giving and receiving has no beginning or end. Therefore it has no start in time, but is timeless. We express this giving of the Father in the Nicene Creed when we say:
“I believe in one Lord Jesus Christ, the Only Begotten Son of God, born of the Father before all ages. God from God, Light from Light, true God from true God, begotten, not made, consubstantial with The Father”
Since the Son is also God and love, He also gives all of himself back to the Father. The mutual self-giving between the Father and the Son is the Holy Spirit, The Third person of the Blessed Trinity. The Holy Spirit "proceeds from the Father and the Son" (Nicene Creed). The Holy Spirit is the Love between the Father and the Son.
We are now ready to better explain the definition of the Trinity, "Three persons in one God." (CCC 253) We have already mentioned the names of the three persons, Father, Son and Holy Spirit. As Catholics we believe in only one God. We are monotheistic (mono: one, theos: God). The definition we began with was only a very simple definition and doesn't include the giving (or relationship) between each person, which is one of love. There are three aspects to the Trinity, person, relationship and unity.
God is personal. God is in fact “Three persons in one God” (CCC 253). There is God the Father, God the Son and God the Holy Spirit. Each person is God. Each divine person is distinct from the others, but not separate since each person is the one God. That is why we don't say each person is an individual, nor can we say 'people' since they are not separate. But each is distinct, ie the Father is not the Son who is not the Holy Spirit. The Catechism states this as, "the term "person" ... designates the Father, Son and Holy Spirit in the real distinction among them” (CCC 252)
God is not just some impersonal spirit. Nor is he some kind of object, but a instead he is a subject, a someone. God being personal means God always relates to us personally. God always relates to each of us with an infinite awareness and concern. This is such an important point when it comes to the Trinity. Unfortunately many people think the doctrine (teachings) of the Trinity are dry and abstract, but each point of Trinitarian doctrine reveals a wonderful message of love. In this case, God being personal, means we can have a real personal relationship with each of the divine persons. God wants to have a personal loving relationship with you, because he is already a personal loving relationship of persons. God always relates directly to us, personally. Every moment of every day is a chance to encounter the living God of love personally.
Each divine person is God, whole and entire. Since all of the Father is given to the Son, the Son is God whole and entire just as the Father is God whole and entire. So too with the Spirit. Jesus is God, the Father is God and the Holy Spirit is God. The Catechism explains it this way:
“The Trinity is One. We do not confess three Gods, but one God in three persons, the "consubstantial Trinity". The divine persons do not share the one divinity among themselves but each of them is God whole and entire” (CCC 253)
Their giving is their unity. The more we share of ourselves the deeper our friendships are, the greater the unity among our friends. The Trinity is the fullness of love since each person shares all that they are with each other. Therefore the Trinity is perfect love and perfect friendship. In God this is total, infinite and perfect, therefore God is a perfect unity and all is not just shared, but each person is God.
There are other words which can be used to expressed the unity of God, which are substance, essence, nature and being. These words are interchangeable when it comes to the Trinity. Each word is used in its own context. The Catechism states, "The Church uses the term "substance" (rendered also at times by "essence" or "nature") to designate the divine being in its unity” (CCC 252).
“God is love” (1 Jn 4:8) (This phrase is repeated in 1 Jn 4:16) The definition of the Trinity as "Three persons in one God" misses out on the giving and love between each person.
The greatest act of love that someone can do for another is to die for them. In other words, to give of oneself totally. This is expressed in the definition of love as 'self-gift'. In the Trinity this is total. We have already learnt that God is infinite. This giving has no beginning nor end, just as each person has no beginning nor end. As a human being, we are a person and love is something we do, but we can also hate. ‘What’ I am, is a human being (body and soul). When it comes to God, God is always giving. The ‘whatness’ of God, what God IS, is pure infinite unconditional giving. The ‘whatness’ of God is self-gift, therefore, the ‘whatness’ of God is love, which is self gift. God IS love. Love is something we do, but love is what God is.
The only way God can relate to us is by loving us.
God does not need us since God is already infinite. Therefore God made us to share himself with us for our own sakes. God wants to share all of himself with us just as he shares all of himself with each divine person of the Trinity. God the Father loves us with the same love he has for God the Son, an infinite, total, unconditional love.
For us to share in the love of the Trinity, we need to become like God and give all of ourselves to God and receive all that God is. The more we give of ourselves to God, the more we will be transformed to share more of God. What God most wants is our sin. He wants to enter into those places in our soul where he is not. Reconciliation is THE way we allow God to enter our sin and transform us. Baptism is the first time sacramentally we enter into God and God enters into us. We need to renew our self gift to God everyday. Daily prayer is the way we do that and allow ourselves to be gradually transformed by God's love.
“God himself is an eternal exchange of love, Father, Son and Holy Spirit, and he has destined us to share in that exchange.” (CCC 221)
The Trinity is personal love. God within himself is an infinite self-giving love between three divine persons. This is the basis of this whole formation course and of all Catholic teaching. God wants to have a personal loving relationship with you, because he is already a personal loving relationship of persons. God unconditionally loves you because God is already infinite love. God wants to share all that he is with you because he already shares everything within the Trinity. We can sum up the three doctrines of the Trinity (person, relationship and unity) as personal loving friendship. Since God IS a personal loving friendship, he wants us to experience all that he is and so each of us are called into this personal loving friendship with him and through him with everyone else. This is THE basis for all things Catholic. Just as we have explored this incredible reality of the Trinity so too will we explore the wonderful interconnectedness of Catholic teaching in all its beauty.
"The mystery of the Most Holy Trinity is the central mystery of Christian faith and life. It is the mystery of God in himself. It is therefore the source of all the other mysteries of faith, the light that enlightens them. It is the most fundamental and essential teaching in the "hierarchy of the truths of faith". The whole history of salvation is identical with the history of the way and the means by which the one true God, Father, Son and Holy Spirit, reveals himself to men "and reconciles and unites with himself those who turn away from sin"." (CCC 234)