Paul's work of evangelization was aimed at establishing communities of believers in Christ. Paul preferred the word "ekklesia" because it implied directly the idea of a call "ab extra" (from the outside). Believers are called by God, who gathers them in a community, His Church.
The Pauline concept of the Church as "Body of Christ" has two dimensions. Firstly, there is the sociological character, which appears in Paul's Letter to the Romans and his First Letter to the Corinthians. All members, even the smallest and apparently insignificant, are necessary for the body to be able to live and to realize its proper functions. The Apostle observes that in the Church there are many vocations, "all necessary to build the living unity of this spiritual organism."
Secondly, the Church is not only an organism, but truly becomes the body of Christ in the Eucharist. There is the realization of the spousal mystery, where all become one body and one spirit in Christ.
Paul demonstrates that the Church is the body of Christ, the "Church of God" and "temple of God." The Pope said that the relationship between Church and temple has two dimensions: those of a sacred building and physical space. Pope Benedict stated, "If before temples were considered places of the presence of God, now one knows and sees that God does not live in buildings made of stone. The place of the presence of God in the world is the living community of believers."
The Holy Father concluded by recalling Paul's Letter to Timothy, in which Paul describes the Church as "house of God." This definition refers to the Church as a community structure, in which there are warm interpersonal relations of a familiar character. The greatness of the Church and of a Christian's calling is that Christians are a temple of God in the world, a place where God is truly present, as well as a family of God, which must realize God's love in the world.