"I am the Vine and you are the branches..."
All who have been baptized into Christ have been clothed with Christ, and not only clothed: indeed, they have become members of Christ, members of His Body, the Church. "One cannot have God for his Father without having the Church for his Mother" (St. Cyprian). "Wherever two or more of you are gathered, there am I in the midst of them." So we proclaim when we venerate the Cross at the end of Liturgy: "Christ is among us." "He is and will be." So He is in the midst of the Church, and so He is in the midst of two or more of the baptized who call upon His name; then we could say that each group of two or more, each Christian community, are a form of mini-Church, a micro-ecclesia, which is united to the remainder of the Church.