St. Athanasius on Church Unity

St. Athanasius the Great ca. 297-373

For as the psalmist says, what is so good or pleasant as for brethren to dwell in unity. But our dwelling is the Church, and our mind ought to be the same. For thus we believe that the Lord also will dwell with us, who says, ‘I will dwell with them and walk in them’ and ‘Here will I dwell for I have a delight therein.’ But by ‘here’ what is meant but there where one faith and religion is preached? (Tomus ad Antiochenos, 1)