The first century of the Christian era begins with the birth of Jesus Christ from the Virgin Mary in Bethlehem, Christ lived, died, rose again and ascended into heaven in the first century. This time also witnessed the outpouring of the Holy Spirit upon Christ's disciples on the feast of Pentecost, the event which is often called the birthday of the Church.
In the first century, the apostles preached the Gospel of Christ. We do not know exactly where the apostles traveled, with the exception of Saint Paul whose missionary journeys are recorded in the book of Acts. According to Tradition, all of the apostles were universal preachers of the Gospel, who, with the exception of Saint John, were killed for their faith in Christ. The gospels and epistles and all of the books which comprise the New Testament scriptures were written in the first century. Also at this time, the first Christian communities were established in the main cities of Asia Minor and Greece, and most probably in North Africa. The Church was also established in the capital city of Rome.
Contrary to what is sometimes thought, the Christian Church was first an urban phenomenon which only later spread to the rural areas. Also, it was composed mainly of people from what we would call today the "higher classes" of society. Thus, it is not true that Christianity gained its foothold in the world in uneducated and backward people who were looking for heavenly consolation in the face of oppressive and unbearable earthly conditions.
The main event of the Church of the first century was the admittance of gentiles into the Church who were not obliged to follow the ritual requirements of the Mosaic law (see Acts 15, Galatians, Romans), Thus, although the Christian Church entered Roman imperial society "under the veil" of Judaism, it was quickly separated from the Jewish faith as the People of God called from all the nations, those who were united in Christ the Messiah, Who was confessed as the Lord and Savior of all men and the whole world.
The requirements for entry into the Christian Church were faith in Jesus as Lord and Christ, repentance from sin, and baptism in Jesus' name with the subsequent reception of the gift of the Holy Spirit. Those who fulfilled these requirements entered the Church which was founded in each place as a local community led by those called bishops or presbyters who received the laying-on-of-hands from the apostles. The apostles themselves were not local bishops of any particular Christian community in any place.
Each of the early Christian communities that we know about had its own unique character, and its own unique problems, as we see in the New Testament documents. Generally speaking, however, each church had great concern for the others and were all called to teach the same doctrines and to practice the same virtues, living the same life in Christ and the Holy Spirit.
And they devoted themselves to the apostles' teachings, and communion, to the breaking of the bread, and the prayers.This description of the Church in Jerusalem can generally be applied to all of the early Christian communities.
And all who believed were together and had all things in common; and they sold their possessions and goods and distributed them to all, as any had need (Acts 2:42, 44).