Ephesians 4:5

This contains some more reasons why Christians should love one another. We are all servants of the same God, believe the same mysteries, and receive the same sacraments, whoever may be the dispenser of them. --- One faith. As rebellion is the bane of commonwealths and kingdoms, and peace and concord the preservation of the same; so is schism, and diversity of faith or fellowship in the service of God, the calamity of the Church: and peace, unity, and uniformity, the special blessing of God therein. St. Cyprian, in his book on the unity of the Church, writeth thus: "One Church, for one is my dove. This unity of the Church, he that holdeth not, doth he think he holdeth the faith? He that withstandeth or resisteth the Church, he that resisteth Peter's chair, upon which the Church was built, doth he trust that he is in the Church?" And again, Ep. xl. "There is one God, and one Christ, and one Church, and one chair, by our Lord's voice founded upon Peter. To set up another altar, or to constitute another priesthood, besides the one altar and the one priesthood, is impossible. Whosever gathereth elsewhere scattereth. It is adulterous, it is impious, it is sacrilegious, whatsoever is instituted by man to the breach of God's disposition. Get ye far from such men: they are blind, and leaders of the blink." St. Hilary also applies this text against the Arians thus: "Perilous and miserable is it that there are now among them as many faiths as wills, and as many doctrines as manners; whilst modes of faith are written as men will, or as they will, so are understood. Whereas the one truth teaches there is but one God, one Lord, one baptism, and also one faith: hence whilst more faiths are made, they begin by falling from that which is the only faith, and end in having no faith at all." (St. Hilary, lib. ad Constantium Augustum.)