In the early days of Christianity, the understanding of unity was closely tied to the belief in the “one, holy, catholic, and apostolic Church.” The early Christians emphasized the importance of maintaining doctrinal purity and adhering to the teachings of the apostles. Unity was seen as essential for preserving the faith, combating heresy, and being a light to the world. Unity was only possible if the external world could visibly see a unified Church and if that Church could internally resolve disputes between it’s members. Leaders such as the apostles and later bishops played a crucial role in maintaining unity and resolving these disputes. Early Church Fathers such as Ignatius of Antioch did not understand this unity to be simply symbolic but rather believed it to be made manifest through participation in the Eucharist and made visible through our recognition of the authority given by Christ to the bishops, especially the Bishop of Rome (Matt 16:18-19, Jn 21:15-17). Without the Eucharist, we are Christ’s Body in name only. Without an authority to rule definitively on a matter, any disagreement among members could ultimately lead to dissolution of Church unity (Matt. 12:25, 1 Tim 3:15, Matt 18:17). Despite some early challenges and disagreements, the early church strove to maintain unity through councils, epistles, and communication among different Christian communities.
Christ Himself taught the importance of unity. Christ even prayed for future believers that they “may become perfectly one” (John 17:20-23). The Church, as Christ’s mystical body on earth, is united as one body of believers (Jn 17:20–23, 1 Cor. 12:-12-13, Phil. 2:2, Eph. 4:5-6). St. Paul pleaded that this principle be put into action. “I appeal to you, brethren, by the name of our Lord Jesus Christ, that all of you agree and that there be no dissensions among you, but that you be united in the same mind and the same judgment” (1 Cor. 1:10). He begged believers to “maintain the unity of the Spirit in the bond of peace” (Eph. 4:3) and taught that the Church established by Christ was to be of one mind and in full accord (Phil. 1:27, 2:2). St. Peter, too, asserted to “all of you [Christians], have unity of spirit, sympathy, love of the brethren, a tender heart and a humble mind” (1 Pet. 3:8). Love of the brethren and faithfulness to God demand unity amongst believers. How can Christians be witnesses of the truth of Christ when all the world sees are divisions?
This unity is only possible if there is a visible Church of divine origin with an authority to settle disputes. Christ’s Church would indeed be a visible Church as Jesus said his Church would be “the light of the world” and that “a city set on a hill cannot be hid” (Matt. 5:14). When the Church is described as “visible” and “one”, it means that it has a tangible, observable presence in the world, expressed by its unified body of believers. This visibility refers to the outward manifestation of the Church through its physical structures, worship services, sacraments, ministries, shared beliefs and doctrines, and the collective actions of its members. The visible nature of the Church allows it to be seen, recognized, and experienced by people in a tangible way.
This visible unity is only maintained by the authority given to the Church by Christ to resolve internal disputes (see Church Authority). In Matthew 16:18, when Jesus says to Peter, “You are Peter, and on this rock I will build my church”, He is establishing His Church. It is this Church instituted by Christ that He refers to in Matt. 18:17 when He says that if your brother resists your attempts to correct him, you must “tell it to the church; and if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector.” For the Church to be the final court of appeals for Christian disputes, it must be a Church recognizable by all Christians as an authority. Any Christians who dissent from this church are excommunicable and their teachings condemned as works of the flesh (Gal. 5:19-21). This visible Church can be clearly seen resolving disputes throughout the book of Acts, as in the case of the circumcision controversy. When the Church decided against this practice, the decision was binding on all Christians, as Christ said; “If he refuses to listen even to the church, let him be to you as a Gentile or a tax collector. Truly, I say to you, whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven” (Matt. 18:17-18). In Jewish tradition, this language denotes judicial authority (see Deuteronomy 17:6-12). The Church can only exercise judicial authority to excommunicate someone if there are visible boundaries to it’s membership.
Early Protestants recognized the importance of unity and have made many attempts at claiming some semblance of unity. These attempts are made manifest in the many confessions of faith put forth by early Protestantism, such as the Augsburg Confessions, Westminster Confessions of Faith, the Canons of Dort, and the Thirty-Nine Articles. Non-Catholic Christians have also unwittingly recognized the Church’s authority and guidance by the Holy Spirit, (although unintentionally), when it comes to the Church’s decisions in the fourth and fifth centuries on what books belong in the Bible, or defining christological and trinitarian doctrines.
Sin Within the Church:
The belief in visible unity through the exercise of authority differs drastically from the kind of moral impeccability demanded within some rigorist groups such as DONATISM and PURITANISM. Although Christians are to respect and obey the Church’s authority (1 Thess. 5:12, Hebrews 13:17), this does not preclude the fact that there are sinners in the Church and its hierarchy. Although the Church has been given authority over its teachings, it does not possess moral impeccability. Christ never promised that His Church would be free of sinners, or that it’s leaders would be without any moral issues. Although Christ pointed out the Pharisees hypocrisy, he still told His disciples to follow their teachings (Matt. 26:1-4). While we are to break communion with those who obstinately refuse to recognize Church authority and spread false teaching, we are not called to break communion with sinners. When the servants of the householder in the parable of the wheat and weeds asked permission to weed the wheat fields (representing the Church), he told them, “No; lest in gathering the weeds you root up the wheat along with them” (Matt. 13:29). Should the earliest Christians have rejected the apostles because Judas betrayed their Lord? Our assent to the Church is not due to its lack of sin, but rather it’s teaching authority given to it by Christ and guided by the Holy Spirit. (John 16:13).
“It is to be numbered among the evils of our day, that the churches are so divided one from another, that there is scarcely any friendly intercourse strengthened between us; much less does that holv communion of the members of Christ flourish, which all profess with the mouth, but few sincerely regard in the heart.
Thus it comes to pass, that the members being divided, the body of the church lies disabled. Respecting myself, if it should appear that I could render any service, I should with pleasure cross ten seas, if neces-sary, to accomplish that obiect.” -Letter XVII: Calvin To Cranmer, Archbishop Of Canterbury, Wishes Health; in Théodore de Bèze, The Life of John Calvin. Translated by Francis Sibson (Philadelphia,
PA: Wm. S. Martin, Printer, 1836), 297-298.