Community is a theme that runs throughout Scripture. God has always been calling out a people for Himself, beginning with Israel and continuing with the church. Even when the Jews were dispersed among enemy nations during times of captivity, they organized themselves into groups and ultimately formed synagogues (Jewish communities of worship and teaching), where they could serve one another and carry out their beliefs. It was natural, therefore, for Jesus to develop a community of followers and for Paul, Peter, and other church planters to start new communities wherever they went as they proclaimed the Gospel. These new communities began as small groups, just as Jesus had modeled with the twelve disciples (Mark 3:14; Luke 6:12-19).
Small groups were an integral part of the early church structure. They were small enough to allow individual members to minister to one another, use their spiritual gifts, and be discipled in the teachings of Christ. In addition, they were vibrant and life-giving communities where evangelism could take place as unchurched people watched a loving and compassionate community in action. Small groups not only built up the church as the first living examples of biblical community but were vehicles for reaching a lost world for Christ.
–Bill Donahue