“A friend of mine who is thinking about becoming Catholic asked me why Catholics believe that the Catholic Church is the one true church, founded 2,000 years ago by Jesus Christ himself. What should I tell her?”
We need to answer a basic question first, “Did Jesus found a church?” He did as we read in Matthew’s Gospel, “I call you Peter, and upon this rock I will build my church” (Matthew 16:18). What was the structure of the church that Jesus founded? Jesus told Peter, “I will give you the keys to the kingdom of heaven, whatever you bind on earth will be bound in heaven and whatever you loose on earth will be loosed in heaven” (Matthew 16:19). In the act of Jesus giving the keys to the kingdom of heaven to Peter, he is giving him authority in the church.
All the apostles were disciples of Jesus. At one point in his ministry, Jesus chose 12 of his disciples and called them “apostles” (which means “one who is sent”) (Matthew 10:1-4). The number 12 is significant. The nation of Israel, God’s chosen people, was composed of 12 tribes. Each tribe had a “patriarch,” one of the 12 sons of Jacob, the grandson of Abraham. In choosing 12 apostles, Jesus is founding a new Israel, a new people of God.
After the Resurrection, Jesus confronts Peter for his three-time-denial that he even knew Jesus. On the shores of the Sea of Galilee, Jesus asks him three times, “Peter, do you love me?” When Peter responds, “Yes, Lord, you know that I love you,” Jesus says, “Feed my lambs” (John 21:15-17). Peter is given the ministry of tending Jesus’ flock, which is his church.
In the Acts of the Apostles, we find Peter and the other apostles exercise authority over the church. After Jesus commissioned the Apostles to continue his work, someone had to be chosen to take Judas’ place. Peter led the nomination and election process that chose Matthias to replace Judas (Acts 1:15-26). When a major question needed to be addressed by the church, the apostles convened to deal with the situation, and Peter led the proceedings (Acts 15:1-12).
The apostles needed to pass on their authority to others, and they did. The clearest examples of this are Timothy and Titus, whom the apostle Paul ordained. We call these successors to the apostles, bishops.
We know that the Catholic Church is the one true church because the Catholic Church’s teachings have remained unchanged since the very beginning. Everything the church believes was believed by the early church (and we have testimony to this fact both from Scripture and from the writings of Christians who came shortly after the apostolic period).
The Catholic Church remained the only Christian Church until the East-West Schism of 1054 that caused medieval Christianity to split and to become two separate branches. The greatest division came during the Reformation from 1517-1648, led by Martin Luther and Henry VIII.
The Catholic Church gave us the Bible. The first official list of books contained in the Bible was proclaimed at the Council of Hippo in 393 and then again in Carthage in 397 and 419. The Council of Trent in 1556 was the first time the church infallibly defined these books as “inspired” because some Reformers questioned the validity of some books.
Other indications that the church is the one true church: Jesus gave the Apostles the power to “forgive sins” (John 20:23). Peter taught that “baptism now saves you” (1 Peter 3:21). Anointing the sick with oil was shown in James 5:14-15. Laying on of hands was seen in Acts 8:17 and 2 Timothy 1:6. Marriage in the Lord is found in 1 Corinthians 7:39. Jesus often stated that the disciples should participate in the breaking of bread (Eucharist) by stating, “Those who eat my flesh have eternal life.”
To sum up, the church is the congregation of all baptized persons united in the same true faith, the same sacrifice, and the same sacraments under the authority of the sovereign pontiff and the bishops in communion with him. This is why we are the true church.