How is the Church “one”? “The Church is one because of her source: ‘the highest exemplar and source of this mystery is the unity, in the Trinity of Persons, of one God, the Father and the Son in the Holy Spirit.’ The Church is one because of her found: for ‘the Word made flesh, the prince of peace, reconciled all men to God by the cross,…restoring the unity of all in one people and one body.’ The Church is one because of her ‘soul’: ‘It is the Holy Spirit, dwelling in those who believe and pervading and ruling over the entire Church, who brings about that wonderful communion of the faithful and joins them together so intimately in Christ that he is the principle of the Church’s unity.’ Unity is of the essence of the Church: ‘What an astonishing mystery! There is one Father of the universe, one Logos of the universe, and also one Holy Spirit, everywhere one and the same; there is also one virgin become mother, and I should like to call her ‘Church’.” [1]

What are these bonds of unity? While the church is “one” in nature, because of Her worldwide expanse, much diversity exists as well. The Church has always welcomed diversity within her peoples, cultures, gifts, offices, and ways of life, while maintaining unity. However, sin and its consequences threaten the gift of unity. This is why Saint Paul writes to the Ephesians exhorting them to “maintain the unity of the Spirit in the bond of peace.” [2] “Above all, charity ‘binds everything together in perfect harmony.’ The unity of the pilgrim Church is also assured by visible bonds of communion:

- profession of one faith received from the Apostles;
- common celebration of divine worship, especially of the sacraments;
- apostolic succession through the sacrament of Holy Orders, maintaining the fraternal concord of God’s family.” [3]
 
The Church is also “one” through the one supreme pontiff, first Peter and then his successors. The Second Vatican Council explains: “For it is through Christ’s Catholic Church alone, which is the universal help toward salvation, that the fullness of the means of salvation can be obtained. It was to the apostolic college alone, of which Peter is the head, that we believe that our Lord entrusted all the blessings of the New Covenant, in order to establish on earth the one Body of Christ into which all those should be fully incorporated who belong in anyway to the People of God.” [4]
 
Has there been disunity within the Church of God? Yes. There has been disunity since the beginning of the Church with the Apostles and that has continued through today. “Where there are sins, there are also divisions, schisms, heresies, and disputes. Where there is virtue, however, there also is harmony and unity, from which arise the one heart and one soul of all believers.” [5]
 
How are we supposed to treat Christians that are not in unity or one with the Church? We are supposed to treat them with dignity and respect because, like us, they are created in the image and likeness of God. “All who have been justified by faith in Baptism are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers in the Lord by the children of the Catholic Church.” [6]
 
How do we work towards unity? “Christ always gives his Church the gift of unity, but the Church must always pray and work to maintain, reinforce, and perfect the unity that Christ wills for her. This is why Jesus himself prayed at the hour of his Passion, and does not cease praying to his Father, for the unity of his disciples: ‘That they may all be one. As you, Father, are in me and I am in you, may they also be one in us,…so that the world may know that you have sent me.’. The desire to recover the unity of all Christians is a gift of Christ and a call of the Holy Spirit.” [7]
 
MOVIE – Remember the Titans
In this clip the coach takes his football team who is divided by race on a run into the battlefield of Gettysburg. He instructs them to learn from the past and to become one team. G.K. Chesterton wrote, “it ought to be the oldest things that are taught to the youngest people” [8] When we strive to bring unity we must remember our past and learn from it so we do not make the same mistakes as our ancestors have. We should always strive to be one.
 
What things should we do to help bring unity in the one Church? By our Baptism and Confirmation, Catholics are called to work to bring the flock back to one fold by ways including:
 
- “A permanent renewal of the Church in greater fidelity to her vocation; such renewal is the driving-force of the movement toward unity;
 
- A conversion of heart as the faithful ‘try to live holier lives according to the Gospel’; for it is the unfaithfulness of the members to Christ’s gift which causes divisions;
 
- Prayer in common, because ‘change of heart and holiness of life, along with public and private prayer for the unity of Christians, should be regarded as the soul of the whole ecumenical movement, and merits the name ‘spiritual ecumenism;’’
 
- Fraternal knowledge of each other;
 
- Ecumenical formation of the faithful and especially of priests;
 
- Dialogue among theologians and meetings among Christians of the different churches and communities;
 
- Collaboration among Christians in various areas of service to mankind. ‘Human service’ is the idiomatic phrase.” [9]
 
Why do we pray for the Church to be one? We recognize that without the Church, we cannot receive Christ, and without Her, we cannot be saved. We should all strive to resolve any ruptures or disconnects to the Church, but realize that it is only through the power of God that this is possible. For this reason, we place our prayers and hopes “in the prayer of Christ for the Church, in the love of the Father for us, and in the power of the Holy Spirit.” [10]

[1] CCC 813
[2] Eph. 4:3
[3] CCC 815
[4] UR 3.5
[5] Origen, Hom. In Ezech. 9, 1: PG 13, 732
[6] CCC 818
[7] CCC 820
[8] Chesterton, What’s Wrong With the World?
[9] CCC 821
[10] UR 24.2