The Apostolic sees claim to have been founded by one or more of the apostles of Jesus, who are said to have dispersed from Jerusalem sometime after the supposed crucifixion of Jesus, c. 26–36, perhaps following the Great Commission. Early Christians gathered in small private homes, known as house churches, but a city's whole Christian community would also be called a church – the Greek noun ἐκκλησία literally means assembly, gathering, or congregation but is translated as church in most English translations of the New Testament.
Many of these Early Christians were merchants and others who had practical reasons for traveling to northern Africa, Asia Minor, Arabia, Greece, and other places. Over 40 such communities were established by the year 100, many in Anatolia, also known as Asia Minor, such as the Seven churches of Asia. By the end of the first century, Christianity had already spread to Rome and major cities in Armenia, Greece and Syria, serving as foundations for the expansive spread of Christianity, eventually throughout the world.
Jerusalem was the first center of the church, according to the Book of Acts, and according to the Catholic Encyclopedia: the location of "the first Christian church". The apostles lived and taught there for some time after Pentecost. Jesus' brother James was a leader in the church, and his other kinsmen likely held leadership positions in the surrounding area after the destruction of the city until its rebuilding as Aelia Capitolina, c. 130, when all Jews were banished from the city. In about 50, Barnabas and Paul went to Jerusalem to meet with the "pillars of the church": James, Peter, and John. Later called the Council of Jerusalem, this meeting, among other things, confirmed the legitimacy of the mission of Barnabas and Paul to the gentiles, and the gentile converts' freedom from most Mosaic law, especially circumcision, which was repulsive to the Hellenic mind. Thus, the Apostolic Decree (Acts 15:19–21) may be a major act of differentiation of the Church from its Jewish roots, though the decree may simply parallel Jewish Noahide Law and thus be a commonality rather than a differential. In roughly the same time period Rabbinic Judaism made their circumcision requirement of Jewish boys even stricter.
When Peter left Jerusalem after Herod Agrippa I tried to kill him, James appears as the principal authority. Clement of Alexandria (c. 150–215) called him Bishop of Jerusalem. A second-century church historian, Hegesippus, wrote that the Sanhedrin martyred him in 62.
In 66, the Jews revolted against Rome. Rome besieged Jerusalem for four years, and the city fell in 70. The city was destroyed, including the Temple, and the population was mostly killed or removed. According to a tradition recorded by Eusebius and Epiphanius of Salamis, the Jerusalem church fled to Pella at the outbreak of the First Jewish Revolt (see: Flight to Pella).; According to Epiphanius of Salamis, the Cenacle survived at least to Hadrian's visit in 130. A scattered population survived. The Sanhedrin relocated to Jamnia. Prophecies of the Second Temple's destruction are found in the synoptics, specifically in the Olivet Discourse.