The praise of unity
For if I in this brief space of time, have enjoyed such fellowship with your bishop — I mean not of a mere human, but of a spiritual nature— how much more do I reckon you happy who are so joined to him as the Church is to Jesus Christ, and as Jesus Christ is to the Father, that so all things may agree in unity! Let no man deceive himself: if any one be not within the altar, he is deprived of the bread of God. For if the prayer of one or two possesses such power, how much more that of the bishop and the whole Church! He, therefore, that does not assemble with the Church, has even by this manifested his pride, and condemned himself. For it is written, “God resists the proud.” Let us be careful, then, not to set ourselves in opposition to the bishop, in order that we may be subject to God.
Source: Epistle to the Ephesians (New Advent)