After Jesus’ death, his followers traveled to spread his teachings as a burgeoning religion. The apostle Paul made the radical shift to proselytize to Gentiles (non-Jews) which advanced the global spread of Christianity as more people joined the Christian community of the church.
Fifty days after the resurrection, the disciples were together in Jerusalem. It was then, at the time of the Jewish spring harvest festival of Shavuot, seven weeks after the holiday of Passover, that they experienced the empowerment that would make them a new community. That day became known as Pentecost in the Christian church and celebrated as the “birthday of the Church.” In the New Testament, the “Acts of the Apostles,” written toward the end of the 1st century by the author of the Gospel of Luke, tells the story of the early church, beginning with this event. There in Jerusalem, where people gathered from many lands for the festival, the new community experienced the outpouring of the Holy Spirit, described as tongues of fire settling on their heads and enabling them to speak the good news of Jesus in all the languages on earth (Acts 2:4). It was an experience of empowerment which transformed a fearful and somewhat confused group of disciples into apostles, those who are sent to give testimony to their faith (apostolos means "messenger" in Greek).
The expansion of the early church was also given energy by the conversion of a Jewish tentmaker named Saul. According to the Acts of the Apostles, Saul had been a persecutor of Christians until he experienced the blinding light of God’s presence as he traveled on the road from Jerusalem to Damascus. He became baptized as a Christian. For the rest of his life, he traveled the Mediterranean world nurturing small communities of Christians until he finally brought the gospel to Rome. He spoke in synagogues and to communities of Jews, affirming his faith in Christ as Messiah. However, he also spoke to Gentiles—those who were not Jews—because he was convinced that the message of new life in Christ was not for his people alone, but for men and women everywhere. As an apostle to the Gentiles, he is known by the Roman form of his name, Paul.
Paul’s controversy with Peter and the community in Jerusalem was of utmost importance for early Christianity, as it gradually became differentiated from its Jewish roots. Paul insisted that new Greek converts need not first become circumcised Jews and keep Jewish food and calendrical law in order to become Christians. In this he disagreed with Peter, whom he understood to be the apostle to the Jews. A council in Jerusalem (about 50 CE) decided in agreement with Paul: Gentiles could become Christians, just as they were, without becoming circumcised Jews first. With this, the door was opened for a new kind of Christian community. Paul’s letters to the new churches of the Hellenistic world have become an integral part of the New Testament.
The Christian community is called the “church.” The word in Greek was ecclesia, those who were “called out.” They were called out of their former lives into a new community. The Book of Acts (2:44-47) describes the life of the first Christian community: “All who believed were together and shared all things in common, sold their possessions and goods and distributed them to all, as any had need. And day by day attending temple together, breaking bread in their homes, they partook of food with glad and generous hearts, praising God and having favor with all the people. And the Lord added to their number day by day those who were being saved.”
In its largest sense, the church is universal—the community of all people who profess faith in Christ. This is what is meant by the term “catholic,” with a lowercase "c," which simply means “universal.” In its most intimate sense, the church is “wherever two or three are gathered” in the name of Christ (Matthew 18:20). Whether universal or a gathering of two or three, the church is a community of people. The images of community in the New Testament are powerful, organic images of belonging. Most important, the church is described as “the body of Christ.” As Paul puts it, “For just as the body is one and has many members, and all the members of the body, though many, are one body, so it is with Christ” (I Corinthians 12:12). Not all parts of the body of Christ, the church, have the same function, but all are members one of another, suffering together, rejoicing together. This powerful metaphor is extended through the central ritual of the community, the blessing and sharing of bread and wine. The bread is called the “body of Christ,” and the wine “the cup of the new covenant.” As the bread and wine are one, so do those who share them affirm their oneness (I Corinthians 11:23-25).
Through the preaching of Paul and other missionaries, the new Christian faith grew quickly, spreading throughout the Mediterranean world. Its primary competitor was neither the sects nor mysterious religions of ancient Greece and Rome, but the cult of the emperor, to whom all were required to honor. For Christians, the “Lord” was Christ alone, and worshipping the emperor as Lord was impossible. The new Christian community was seen as subversive because of its refusal to participate in the cult of the emperor. Christians were persecuted and martyred for their faith throughout the Roman empire. Thus, it was a new landscape entirely when, early in the 4th century, the Emperor Constantine himself became a Christian. Beginning with his reign, Christianity was not only made legal, but would become the official religion of the Empire.