BITE-SIZE THEOLOGY (79) – What do we mean when we say that the Church is one?

– Rev José Mario O Mandía

When we recite the Creed, we profess our belief in the unam, sanctam, catholicam et apostolicam Ecclesiam (one, holy, catholic and apostolic Church). What do these characteristics or marks mean?

When we say that we believe in the one Church (credo in unam Ecclesiam), we understand the term unam in two senses: (1)  that it is united – it possesses the gift of unity; (2) that is unique, it is the only one that Christ founded.


The CCCC (no 161) teaches us that there are three reasons for the Church’s unity: “The Church is one because [1] she has as her source and exemplar the unity of the Trinity of Persons in one God. [2] As her Founder and Head, Jesus Christ re-established the unity of all people in one body. [3] As her soul, the Holy Spirit unites all the faithful in communion with Christ.

Where can we see this unity? The same point of the CCCC explains which aspects of the Church show this unity: “The Church has but [1] one faith, [2] one sacramental life, [3] one apostolic succession, [4] one common hope, and [5] one and the same charity.” Within the Church, one finds “a multiplicity of peoples and cultures” and “there are different gifts, offices, conditions, and ways of life” (CCC 814). Despite these differences, all Catholics profess the same faith, they receive the same sacraments, they all trace their belief from the apostles, they struggle to obtain everlasting happiness and to be united in love.


CCC 817 points to the historical fact that “‘in this one and only Church of God from its very beginnings there arose certain rifts, which the Apostle strongly censures as damnable. But in subsequent centuries much more serious dissensions appeared and large communities became separated from full communion with the Catholic Church – for which, often enough, men of both sides were to blame’ (Unitatis redintegratio 3).”

What are we to do in the face of this disunity? The Church herself teaches us that unity can be restored “by conversion of heart, prayer, fraternal knowledge of each other and theological dialogue” (CCCC 164).


Jesus Christ told Simon Peter, “And I tell you, you are Peter,  and on this rock I will build my church, and the powers of death  shall not prevail against it. I will give you the keys of the kingdom of heaven” (Matthew 16:18-19). He spoke of only one church.

The CCCC (no 162) explains Jesus’ words when it teaches: “The one Church of Christ, as a society constituted and organized in the world, subsists in (Latin “subsistit in”) the Catholic Church, governed by the Successor of Peter and the bishops in communion with him. Only through this Church can one obtain the fullness of the means of salvation since the Lord has entrusted all the blessings of the New Covenant to the apostolic college alone whose head is Peter.” 

What about non-Catholic Christians? “In the churches and ecclesial communities which are separated from full communion with the Catholic Church, many elements of sanctification and truth can be found. All of these blessings come from Christ and lead to Catholic unity. Members of these churches and communities are incorporated into Christ by Baptism and so we recognize them as brothers” (CCCC 163).

Does this mean that Catholics should not do anything to help these separated brethren? Not at all. Full communion with the Catholic Church is always to be desired, because our Lord Himself asks and prays for full unity. “And I have other sheep, that are not of this fold; I must bring them also, and they will heed my voice. So there shall be one flock, one shepherd”  (John 10:16).