The Communion of the Church



The idea of Communion is the most basic and essential idea of the Ecclesiology of the Second Vatican Council, the key for profoundly understanding the theology of the Dogmatic Constitution on the Church, and for renewing Ecclesiology in accordance with the spirit of the Council.[1]

This lecture only emphasizes “the core essence of Trinitarian theology of the mystery of the communion Church, with the purpose of offering authentic theological guidance for renewing the Church in Vietnam, which is based on the Bible, Church Fathers, and the Magisterium. In spite of being based on tradition, this lecture aims to open up vivid thinking and concrete application, without worrying about erroneous diversions.

God is “Love.” Love is not an alone and boring object, but loving relationships, loving acts. In God, these relationships and acts are so realistic and complete that they form the particular persons that the Bible reveals to us; that is, the Father, the Son, and the Holy Spirit, whom every Christian believes in and confesses is aware of and loves through baptismal faith.

The Trinity is such a profound “Loving Communion” that they are no longer three, but one. We have only one God, who is the Father, the Son, and the Holy Spirit. These Persons turn to one another, come to one another, abide in one another, are self-giving to one another, stay in one another, and become one in one another.

The Church was born by Trinitarian Love, has lived in, through, and for that Love. The Church is derived from the mystery of Trinitarian Communion and moves towards Trinitarian Communion. The Dogmatic Constitution on the Church states: “The Universal Church is seen to be a people brought into unity from the unity of the Father, the Son and the Holy Spirit.”[2] (LG. 4)


1.1. Communion in accordance with the vertical and the horizontal

The notion of Communion in the Mystery of Communion we confess, is not a notion of a single meaning, but connotes first the vertical, and then the horizontal.[3] Without the vertical, the Church is no longer the Church in Christian meaning, but a community as other worldly communities. With the vertical, Communion brings us to unity with the Trinity; we become one with Jesus in the Holy Spirit and come to be one with God through Jesus. With the horizontal, we are one through uniting with Jesus in the Holy Spirit, forming the Church, the Mystical Body of the Lord.

For the Church, Communion is always a grace. Therefore, Jesus earnestly prayed: “I do not pray for these only, but also for those who believe in me through their word, that they may all be one; even as thou, Father, art in me, and I in thee, that they also may be in us.”[4] The Church receives that grace unceasingly; that is, the grace of Communion, the Holy Spirit of love and consolidation, the fruit of the Father’s salvific loving initiatives, which is conferred on us in Christ’s Paschal Mystery.

Through Baptism we are engaged in Christ’s Mystery of his Passion and Resurrection, dying with Him and rising with Him.[5] In Baptism, not only is the Holy Spirit an Agent engaging us in Christ as vine branches to their trunk so that we are one with the Lord in the Paschal Mystery, but also the Grace of Salvation, the Grace of forgiveness, new Life, which makes us risen with Christ, and Communion Love joining us into one. By the Father’s salvific will, through Christ’s Paschal Mystery, and in the Holy Spirit’s Unity, we are one in the formation of the Church.

Through the Holy Sacrament, we are more profoundly united with Christ, sharing in his Flesh and Blood.[6] Christ himself becomes divine food, “Bread of Life” feeding us. Every Christian lives by Christ’s life and thus becomes a part of Christ’s Body, the Church. Celebrating Mass is celebrating Christ’s Paschal Mystery, dying with Him, so that rising with Him. In the Holy Spirit, we go with Christ towards the Father.

1.2. Communion, visible and invisible

Communion of the Church is both visible and invisible.[7] The invisible aspect is every person’s communion with the Father, through Christ, in the Holy Spirit, and with those who share in the divinity of God (consortes divinae naturae).[8] The visible aspect is done through communion in the “Catechism of Apostles”, in sacramental life, and in the Ecclesiastical Hierarchy.

The clearest visible face is the community of Christians, Jesus’ disciples, who believe and follow Him in his footsteps, being organized hierarchically. The hierarchy in the Church is established by Jesus so as to serve and guide the Church. Jesus establishes the hierarchy in order to serve and guide the Church. The hierarchy does not contrast with communion; on the contrary, it is used by the Holy Spirit only towards serving communion.

The whole Church shares in Jesus’ three functions “priestly, prophetic, and kingly.” However, there are people called to engage more specifically in these three functions, that is, ministers conferred by the Sacrament of Holy Orders; they are engaged in Jesus’ status as head. The Holy Father is a successor of Saint Peter, appointed by Christ as head of the whole Church[9] to be “a communion glue” of the universal Church. Bishops are the successors of the Apostles, being “a communion glue” of the diocese authorized to them.

Both the visible aspect and the invisible aspect of the Church must be considered appropriately in accordance to God’s will, revealed in Jesus Christ. There is such a close relationship between the visibleness and the invisibleness; the former manifests and conveys the latter. The ecclesiastical hierarchy is the sign and the tool serving grace, the sign of God’s salvific Love, the sign of Trinitarian Communion.

Each Christian was born as a son or a daughter of God in the womb of the Ecclesial Mother through the Word of God and the Sacraments; at the same time, they live under the Holy Spirit’s guidance, as Saint Paul says: “For all who are led by the Spirit of God are sons of God.”[10] Each Christian is anointed by the Holy Spirit when he is baptized, so that he becomes the likeness in Christ’s image. Thanks to Christ, they meet in the Sacraments and are filled with the fullness of the Loving Spirit of the Father and the Son.

The Church is the communion of saints,[11] because the baptized are united and share in the same Holy Spirit. They all drink the unique Spirit,[12] that is, the living Water that came out from the pierced side of Jesus.[13] Together with the Holy Spirit, they receive varieties of gifts which are charisms for serving the common benefits of their community.[14]


To understand the traditional catechism of the Church on Communion (Koinonia, Communio) appropriately, we should discriminate on three different levels.

2.1. Participating in the same Spirit(Communio Sancti)

The first level that theology calls “Communio Sancti” is “the share in the same Spirit” or “communion in the Holy Spirit.”[15] We become one with Jesus in the Holy Spirit, and also one with the Father in the Holy Spirit through Jesus.

The Holy Spirit is the “Environment” where we are united with Jesus and the Father. He is “the invisible Environment in the visible Environment, the Church,” so the Fathers of the Church called Him “the Soul of the Church.” It is because of this that the Church becomes the place where man gets in touch with, and is united with, the Trinity.

2.2. Participating in holy reality (Communio sanctorum)

The second level called “Communio sanctorum” is the share in “the holy reality,” getting benefits from the Sacraments, especially eating the same Bread and drinking from the same Chalice in the Holy Sacrament.[16] The salvific economy of the New Testament time is “the economy of Sacrament”; God saves us in the Church through the visible and effective signs, namely Sacraments. God gives us the Holy Spirit through the Sacraments.

Besides the Sacraments, the theology of the Second Vatican Council also puts emphasis on “the Word of God” proclaimed in the Church. It is through listening to the Word of God in Scripture that we encounter the Holy Spirit, the Divine Author of Scripture.

2.3. Communion of Saints (communio sanctorum fidelium)

The third level called “Communio sanctorum fidelium,” is communion between “the saints.” Christians were called “saints” because they were baptized, purified, and became righteous through “the sanctifying Spirit”, whom they received. Every Christian is united with Christ, who died and has risen. They become one with Christ in the Holy Spirit; they are thus one with one another, forming the only Body, the Church.

This communion does not limit itself to the living community in the world, but consists of the communion with “the Curia in heaven” and with the souls in purgatory.[17]

2.4. Intimate relations among three levels

Although three communion levels mentioned above are distinguished from one another, they do not remain separate, but connect with one another, one leans on the other. The Spirit as wind that blows where it wills, but in the economy of salvation for human beings, it is necessary to have visible and effective signs established by Jesus, namely, the Sacraments, in order to confer us with the Spirit.

The Church is a “Community of Christians,” who are connected and united with one another, neither by purely natural friendship nor social contract, but by the relationship of “Holy People” gathered by “Trinitarian Love”, united with God and connected with one another by “Grace of the Spirit” that they receive through the Word of God and the Sacraments.

2.5. The universal Church and the local Churches

The communion mentioned above forms the Church of Christ, the one holy catholic and apostolic Church. This Church subsists in (subsistit in) the Catholic Church that is governed by the successor of Peter and by the Bishops in communion with him.[18] This universal Church is completely present in each local Church (Diocese).

“The Liturgical congregation” is summoned under Bishop’s residing as the sign and the clue of “the unity of a local Church.”[19] “The Local Eucharistic congregation” is the one Church, through the one Spirit and the one body. “There is one Bread, we who are many are one body, for we all partake of the one Bread” (1 Cor. 10:17). Being the holy Church because She is sanctified by the power of the one Spirit. Being the Catholic Church because She manifests the fullness of the mystery of Christ, being present in history so as to reconcile everybody and every species with the Father. Being the apostolic Church because She continues the tradition of the Apostles and undertakes “the mission of the Apostles,” authorized by Christ.[20]

Analogically, we can say about the communion of local Churches with the Roman Church and the communion between the local Churches with one another.[21] The Holy Father is the successor of Peter as the head of “the apostolic corps,” and also the head of “the Episcopal corps;” this communion forms the universal Church. However, it is wrong to consider that the local Churches existed beforehand, when the universal Church is only the sum of the local Churches. It is in the Church of Christ that the universal Church generates the local Churches and exists in the local Churches. The dogmatic formula “Ecclesia in et ex Ecclesiìs” (the Church in and from the Churches), must be supplemented with the other dogmatic formula “Ecclesiae in et ex Ecclesia” (the Churches in and from the Church).[22]


A word in Catholic theology that needs to be emphasized so as to keep our faith in apostolic authenticity is and. It is not the separating word, but the connective word.

1. Unity and diversity

When we talk about the communion in the Church, we call to mind “unity” and “diversity.”[23] There is no choicebetween unity and diversity, no opposition between one and many. If we emphasize the unity too much, we are easily led to imitate servility and uniformity; at the same time, the environment of the parish or diocese possibly stifles innovations and quenches the charism of the Holy Spirit. If we emphasize the diversity too much, we may encounter strife and division.

Here, the Church has to be an “icon” of the Trinity. There is one God who is the Father, the Son, and the Holy Spirit. The Father is not the Son; the Son is not the Holy Spirit; the Father also is not the Holy Spirit. However, three Persons are in one another and together in one.

2. Harmony and contrast

Another case of the word and that needs to be emphasized is, the and staying between harmony and contrast (harmonie et contraste). Is there both harmony and contrast in communion or only one of them, and not any other? Based on Eastern philosophy, we must have agreed that there is neither pure yang nor pure yin. If there is only yin, there will not be harmony; if there is only yang, there will also be no harmony. Yin and yang contrast with each other; harmony between them is the harmony between contrasting things.

If we emphasize the harmony and neglect the contrast, we will frighten off contrasting things, contrasting points of view; even if we assimilate them with opposition and consider them not to be communion. If we emphasize the contrast, we will come to speak only of contrary things; so we will not deliver any constructive thoughts, but only destructive ones. Therefore, we should thoroughly apply the statement of the Holy Father, John XXIII: “In necessariis unitas, in dubiis libertas, in omnibus caritas.”[24] (Unity in essentials, liberty in doubtful matters, charity in all things.)

3. Already and not yet

The word and is also necessarily stressed in dialectic “already and not yet” (déjà and pas encore) in theology. Is the Church of Christ really the communion Church, the sign and the icon of “Trinitarian communion”? Already and not yet. Through and in the Holy Spirit, the Church is already “the Mystery of communion”, the environment of Love, the place of the supreme and the most profound meeting between man and God, as well as between man and man.

However, the Church is still on the journey towards that communion. The aspect of “not yet” is very clear when we look at members of the Church. Many members are still very far from God and from one another. The status of Christians is still a guilty status, though they were sanctified by grace through their belief in Jesus Christ. All members of the People of God still have to labour courageously in order to follow Jesus on his way of Pasch. However long the Church remains in this world, Pasch and communion will accompany each other; we unite with the Lord in order to do Pasch with Him, then through doing Pasch with Him we in turn unite with Him more profoundly.

If we put too much emphasis on the aspect of the already, we will be disappointed when we see cracks, divisions, and conflicts appearing in the Church, both in the past and in the present. Let us consider the aspect of not yet, so that not only are we practical, but that we also strive to advance unceasingly, as well as to pray for “the Grace of communion,” being the Loving Spirit whom God certainly confers on us whenever we beseech Him. Emphasizing the aspect of not yet will direct us towards the coming things, in the direction of the future with the fullness of hope in our hearts because of belief in God’s love, the love greater than sin and stronger than death.


The word communion is rich in content, so we can use different words to express its different aspects. Each aspect has important corollaries for the Christian spiritual life and the ongoing pastoral work of the Church.

4.1. Communion is “participation” (participatio)

Communion primarily is “participation.” We all eat the same Bread, drink from the same Chalice, participate in “the Body and Blood of Christ,” participate in the sacrifice of the Cross of Christ.[25] We all participate in the same Spirit, drink the same kind of Living Water, because we are baptized in the same Spirit so as to become one Body.[26] In the Spirit, we participate in the Lord’s Life, Light, Love, and Power.

The word participation stresses the active aspect of our presence. We join, we have a part, we share in. The word participation emphasizes our rights and responsibilities. We participate in the same Bread, forming the one Body. Not any others, but we ourselves form that Body; of course, with the condition, that is, we join and become one with the Lord and with one another. All of us have to eagerly build up Christ’s Body, the Church. The Church has to be organized in such a way as to have everyone possible participating in it.

4.2. Communion is “partaking” (partage)

Communion is also partaking. The Rite of breaking Bread (Fractio Panis) in the earliest Church only is the Holy Sacrament, being “Bread broken to share with each of us, being the Body of Christ Who sacrificed himself for us. Paul writes: “Because there is one bread, we who are many are one body, for we all partake of the one bread.”[27]

Since communion is sharing and acquiring a share in the same food, the Lord himself, sharing in the same Love and Life of the Lord, our pastoral line must emphasize the aspect of “solidarity and sharing with one another” what we have, even ourself. The common letter of the Episcopal conference of Vietnam in 2004 “Giáo Hội Sống Mầu Nhiệm Thánh Thể” (The Church Lives the Mystery of Eucharist), stresses this aspect of the life of the Church.[28]

4.3. Communion is “unity with” (Communio: Cum-Unio)

The most basic and profound meaning of the word communion is “love”, the joining together, the uniting together, and becoming one together. The pastoral line of communion is the pastoral line of connection, the thinking and acting together, the dialoging and the cooperating with one another.

Love is always the act of connection, but also the liberal act arousing freedom. “Love one another and let others be free.” “Love one another and encourage others to be free.” “Love one another and make others free.”

God loves us and creates us with freedom. We lose our own freedom and become slaves when we sin. Because God loves us, He sends his only Son to free us and make us his liberated children. He gives us the Loving Holy Spirit, the Spirit of sonship, so that we are able to cry: “Abba! Father!”[29] The love of God evokes (calls) the love of man (Amor amorem invocat). The love of man is the love responding to the Love.

4.4. Distinguishing between Communion and Unity

When Paul called Christians to partake in unity, he primarily emphasized the unity of the Church in the one Spirit: “There is one Body and one Spirit, just as you were called to the one hope.”[30] There is one Lord, one faith, one baptism.”[31] There is one God, the Father of us all who is above all, and through all, and in all.”[32]

The Second Vatican Council considers the Church as a Sacrament or a sign, a tool of the intimate union with God and the unity between all human beings.[33]

It is very difficult to distinguish clearly between the two notions of “unity” and “communion.” In spite of this, we should differentiate between them so that we avoid excessive claims by the pilgrim Church and keep a dynamic vision, instead of a static about the Church.

Communion is a work in progress; an operation of love directed towards each other, the exchange of relations with each other, union with each other, being present in each other. Communion is not anything but love and intimate union with each other. The Holy Spirit is a Person of Love, unifying the Father and the Son so intimately and becoming “one substance.” The Holy Spirit which is given to us by the Father and the Son is the divine Power of Love, through whom we are able to love and unite with the Trinity and with one another.

Unity is a state; it is a consequence of love’s mutual progress and action: “being one with others for loving one another.” This state stresses “unity,” “unifying” that is contrary with the state of separation, split, and disintegration. This can occur in a small community such as a family, a society, a nation, or even a religious community, such as a parish, a diocese … because of the lack of love. Unity is peaceful, stable, astate of solidarity between each other because there is no opposition, conflict, or hatred.

We emphasize unity in the Church, because that is the one thing Christ desires and beseeches the Father for. That is also his purpose and ministry: “Jesus should die for the nation and not for the nation only, but to gather into one the children of God who are scattered abroad.”[34] “And I, when I am lifted up from the earth, will draw all men to myself.”[35]

Although we give priority to unity a lot, we should not forget that our God is the Triune God (one Substance but three Persons) and the one Trinity (three Persons but one substance). Trinitarian communion must be the exemplar and model for the Church.


In accordance with the viewpoint of the Christian faith, Love and Truth always accompany or lean on each other. Love must be truthful, otherwise it is not love. There is no deceitful love. God is the truthful Love; there is no deceitfulness in Him. It is the truth of God’s love that sets us free: “If you continue in my Word, you are truly my disciples, and you will know the truth and the truth will make you free.”[36]

Jesus is “the Word of the Loving God,” the Holy Spirit is the Breath of the Loving God.” The Loving God, the Word and the Breath of the Loving God are one. Here, One is not only a number, but also the fullness of love, happiness, and life.

The three Persons of God is the original source of man and the Church. Here too, three is not only a number, but also “a self-exchange,” “a mystical interchange,” “a fullness of the many,” “a living and loving relationship,” “perichoresis of love and life.” The Trinity is also the destined Home of man and the Church.

The Church is God’s family on earth. Therefore, She must be organized in such a way that every member feels he/she is in “his/her family.” “So then, you are no longer strangers and sojourners, but you are fellow citizens with the saints and members of the household of God.”[37]

The Church is the icon of the Trinity. How can everyone recognize the love of God when they look at the Church? Intimate communion between the members of the people of God, is the most certain proof and the most effective sign.[38] “By this all men will know that you are my disciples, if you have love for one another.”[39]


Paul Bui Van Doc

Bishop of My Tho Diocese

[1]See Vatican II, LG 4,8; DV 10; GS 32; UR 2-4; 14-15; 17-19; 22; Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, 28.05.1992, no 1-3.

[2]VaticanII, LG 4.

[3]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 3.

[4]Jn 17:20-21

[5]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 5.

[6]Ibid. no 5; 10.

[7]Ibid. no 4; Vatican II, LG 7

[8]See 2 Pet 1:4

[9]See Mt 16:8

[10]Rom 8:14

[11]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 6; Vatican II, LG 4.

[12]See 1Cor 12:14

[13]See Jn 19:34

[14]See 1Cor 12:4-11

[15]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 6; Vatican II, LG 4.

[16]Ibid., no 5; 10; 11.

[17]Ibid., no 6; 10; 14.

[18]See Vatican II, LG 8.

[19]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 9, 14.

[20]See Bruno Forte, The Church Icon of the Trinity, ST. Paul Publications 1990, p. 90.

[21]See Congregation for the Doctrine of Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, no 7, 8.

[22]Ibid., no 7, 9; Vatican II, CD 6, 11; LG 23.

[23]See Congregation for the Doctrine of the Faith, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion, 28.05.1992, n07; 8.

[24]IOANNIS XXIII, Litterae Encyclicae ad Petri Cathedram, ad Pariarchas, Primates, Archiepiscopos, Episcopos Aliosque locorum Ordinarios, Pacem et communionem cum Apostolica Sede Habentes de Veritate, Unitate et Pace Caritatis Afflatu Provehendis, die 29 mensis Junii, 1959, no 72.

[25]See 1Cor. 10:16

[26]See 1Cor. 2:13

[27]1Cor. 10:17

[28]See Hội Đồng Giám Mục Việt Nam, Giáo Hội Sống Mầu Nhiệm Thánh Thể, Thư chung 01.10.2004.

[29]Rom 8:15

[30]Eph 4:4

[31]Eph 4:5

[32]Eph 4:6

[33]See Vatican II, LG 1.

[34]Jn 11:51-52

[35]Jn 12:32

[36]Jn 8:31-32

[37]Eph 2:19

[38]See Benedict XVI, Letter to the Bishops of the Catholic Church on Some Aspects of the Church Understood as Communion.”

[39]Jn 13:35