The question of where Jesus explicitly teaches that there should be only one Church is only seemingly simple at first glance. Anyone expecting a literal formulation misses the way in which Christ teaches. Jesus speaks as a divine teacher, not as a legislator of a modern code. He does not say in legal language that there will be only one Church, just as he does not literally say that he is divine, even though he clearly testifies to it in substance. The same applies to the Church. Everything Jesus says about his Church, about the community of his disciples, about the truth and about unity, leads only to the conclusion that he wanted one single, concrete Church that exists throughout history.
The decisive sentence (Matthew 16:18) of Jesus is: “You are Peter, and on this rock I will build my Church.” Here he does not speak of many churches, but of a single Church that belongs to him. This word has a clear direction, as the singular is not accidental. Christ does not build several separate communities, but the one house of God, which is to exist through all times. He adds that the powers of the underworld will not overcome this Church. This makes it clear that it is a concrete, historically tangible community that continues unbroken, and not a multitude of contradictory groups that contradict each other in doctrine, sacraments, and authority.
A second decisive passage is found in Jesus’ words (Matthew 18:17): “Tell it to the Church.” This word presupposes a visible institution that decides authoritatively. A multitude of independent communities could not fulfill this task, for to whom should the Christian obey if different churches make different judgments that contradict each other? Here too, unity is not thought of as merely spiritual or invisible, but as concrete and binding.
The unity of the Church becomes even clearer in the image of the shepherd and the flock. Jesus explains that there will be one flock and one shepherd. Since Christ himself is the shepherd, it necessarily follows that there cannot be a variety of contradictory flocks wandering separately from each other. There is only one flock, because there is only one shepherd ministry of Christ, which continues visibly in the world.
Even stronger is the Lord’s statement in the high priestly prayer: “That they may all be one.” This prayer of Jesus is not a vague request for a friendly mood among Christians, but a serious plea for the same unity that exists between Father and Son. Such unity is not merely an inner harmony, but a real unity in faith and confession. According to Christ’s will, this unity is to be a sign for the world, so that it may know that the Father has sent the Son. Divisions destroy this sign. Therefore, the fragmentation of Christianity cannot be an expression of the divine will, but rather shows the violation of this unity.
The apostles unfold this will of Christ in their writings. Paul writes that there is one body and one Spirit, one Lord, one faith, and one baptism. The one body is the Church of Christ. One body cannot consist of separated and contradictory communities that represent different teachings and have different sacraments. The unity of the Church is therefore not a human construct, but a divine mandate.
This truth has always been understood in this way by the great Church Fathers. Augustine, who tirelessly fought against the Donatist schism, emphasizes that there is only one Church, the catholic and universal community that lives in unity with the legitimate bishops. For him, the Church is the one bride of Christ. Christ cannot have many brides, and therefore there cannot be many separated Christian communities, each claiming to be the true bride. Jerome states that where the legitimate bishop is, there is the Church, and that unity with the See of Peter is the visible bond of unity. Leo the Great sees in the ministry of Peter the source of ecclesial unity. Christ appointed Peter as the rock so that the Church would remain undivided. Gregory the Great describes the unity of the Church as the unity of the shepherds under the one shepherd Christ and as the unity of the local churches under the successor of Peter.
The Eastern Church Fathers also teach this truth. Chrysostom sees every schism as an attack on the body of Christ. Cyril of Alexandria teaches that unity in truth and apostolic tradition is essential to the Church, since the Church is the body of the one Christ. Saint Ignatius of Antioch, the disciple of the Apostle John, explicitly calls the Church the Catholic Church and declares that where the bishop and the Eucharist are, there is Christ. For him, unity is not an option, but a divine command.
Thomas Aquinas describes the unity of the Church as a necessary consequence of the fact that Christ is its head. Just as there is only one Christ, so there is only one mystical body. The unity of this body is preserved through the one faith, the common sacraments, and the unity of governance. For Thomas, the Pope is not an external addition, but the visible guarantor of the unity willed by Christ.
Later tradition confirms this. Robert Bellarmine defines the Church as the visible community of those who profess the same faith and are in unity with the Pope. Francis de Sales shows against the Reformers that the Church of Christ is visible, recognizable, and undivided.
In summary, the entire Scripture and the entire tradition show: Christ did not will many churches, but one single Church, founded by him, led by the apostles, and kept in unity by the successors of Peter. The one Church is the one body of Christ. Therefore, one can truly say: Jesus did not want a multitude of churches, but one, holy, catholic, and apostolic Church, which remains visible in history and lives in the unity of faith.