How were the Pentecost, the Great Commission, the ruling of the Council of Jerusalem, St. Peter and St. Paul significant in the life of the early church?

Pentecost
Pentecost is a festival that commemorates the arrival of the Holy Spirit. Its name is derived from the Greek word for “fiftieth”, as it occurs fifty days after Passover, during the Jewish festival Shavuot. The original Pentecost is described in the Book of Acts, when the Holy Spirit descended to the apostles and appeared over them in the form of “tongues of fire.” The apostles then began to speak in foreign languages; this phenomenon, called glossolalia, is still recognized by some modern sects of Christianity as proof that a believer has been baptized in the Holy Spirit.
Great Commission
The Great Commission is the moment when the resurrected Jesus appeared before his apostles and instructed them to travel the world and spread his message, baptizing all who would accept it in the name of the Trinity. This evangelistic mission is at the heart of Christianity, which sees itself as responsible for seeking out anybody who has not heard its message.
Council of Jerusalem
Christianity has classically mediated disputes and pronounced judgments on matters of belief and action through the mechanism of councils. The Council of Jerusalem was the first of these, convened to define the relationship between traditional Judaism and the new Christian sect emerging within Judaism. The ultimate decision was that non-Jews did not need to first convert to Judaism in order to become Christians, nor did they need to follow the traditional Jewish law. This helped to differentiate Christianity as a unique religion.
St. Peter
Peter, first named Simon, is remembered in Catholic tradition as the first pope, or chief bishop of the church. Throughout Christianity, he is celebrated as one of the chief apostles. Jesus gave him the name “Peter," which means “rock," declaring that Peter would be the rock on which he built his church. Peter is also remembered as the apostle who denied knowing Jesus on the night before his crucifixion.
St. Paul
Paul was a convert to Christianity after the death and resurrection of Jesus. According to the Book of Acts, he was originally a Jewish persecutor of Christians who was later converted after a supernatural encounter with the resurrected Jesus. After this encounter, he became a fervent advocate of Christianity and is credited with writing the majority of the letters that make up the New Testament. He is foundational in helping define Christian belief and practice, and he founded a number of Christian communities across the Greek and Roman world.