A Manual of Catholic Theology on the Unity of the Church

SECT. 241.—The Unity of the Church

It is so clear from the Holy Scriptures that the Church of Christ must be one, that no Christian can venture to deny it. The great question is—What sort of unity did our Lord will for His Church? As the Church is a visible society, the union must also be visible and external. Moreover, it must be a union of belief not simply in certain so-called fundamental doctrines, but in all revealed truths. And again, it must be not a loosely confederated union of different Churches, but one single Church, one body and one spirit, one Lord, one faith, one baptism, one fold, and one Shepherd—one, that is, in communion, one in faith, and one in worship. “The Church in respect of its unity,” says St. Clement of Alexandria, “belongs to the category of things indivisible by nature, though heretics try to divide it into many parts. We say, therefore, that the Catholic Church is unique in its essence, in its doctrine, in its origin, and in its excellence.… Furthermore, the eminence of the Church arises from its unity, as the principle of its constitution—a unity surpassing all else, and having nothing like unto it or equal to it” (Strom., lib. vii. c. 17).

I. Our Lord’s prayer at the Last Supper (John 17:11–23) is not merely an ineffectual wish, but an efficacious cause of that for which He asked. “All My things are Thine, and Thine are Mine,” He said to His Father; and He expressly stated that the unity of His followers was to be a sign of the Divinity of His mission. “Holy Father, keep them in Thy Name … that they may be one, as we also are … that they may be one, as thou, Father, in Me, and I in Thee; that they also may be one in us; that the world may believe that Thou hast sent Me.” Again, Christ spoke of His Church as a Kingdom (Matt. 16:17; cf. John 18:36 sqq.), and He said, “If a kingdom be divided against itself, that kingdom cannot stand” (Mark 3:24). He called it also the one Fold under the one Shepherd (John 10:16). By St. Peter it is styled a House (1 Pet. 2:5); “If a house be divided against itself, that house cannot stand” (Mark 3:25). St. Paul says God “hath made Him (Christ) Head over all the Church, which is His mystical body” (Eph. 1:22, 23). Of this body he says, “All the members of the body, whereas they are many, yet are one body, so also is Christ; for in one Spirit we were all baptized into one body” (1 Cor. 12:12, 13); and of this mystical body, “The Head, Christ; from Whom the whole body being compacted and fitly joined together by what every joint supplieth, according to the operation in the measure of every part, maketh increase of the body unto the edifying of itself in charity” (Eph. 4:15, 16). “As in one body we have many members, but all the members have not the same office, so we, being many, are one body in Christ, and every one members one of another” (Rom. 12:4, 5). No stronger language could be used to bring out the compactness, the close union, of the members of Christ’s Church. Anything like a vague agglomeration of different bodies is absolutely excluded. “There is one God and one Christ,” says St. Cyprian, “and His Church is one, and the faith is one, and one the people joined together in the solid unity of the body in the bond of concord. This unity cannot be broken, nor the one body divided by the separation of its constituent parts” (De Unit. Eccl., n. 23). And St. Augustine: “See what you must beware of—see what you must avoid—see what you must dread. It happens that, as in the human body, some member may be cut off—a hand, a finger, a foot. Does the soul follow the amputated member? As long as it was in the body it lived; separated, it forfeits its life. So the Christian is a Catholic so long as he lives in the body; cut off from it, he becomes a heretic—the life of the spirit follows not the amputated member” (Serm. cclxvii. n. 4).

II. 1. “Agreement and union of minds is the necessary foundation of this perfect concord among men, from which concurrence of wills and similarity of action are the natural results. Wherefore in His Divine wisdom He ordained in His Church unity of faith: a virtue which is the first of those bonds which unite man to God, and whence we receive the name of the Faithful” (Leo XIII., Encycl., Satis cognitum)., As the Church is one, and as she is the union of those that believe, it follows that her faith must be one. “One faith,” says St. Paul (Eph. 4:5). And again: “I beseech you, brethren, by the Name of our Lord Jesus Christ, that you all speak the same thing, and that there be no schisms among you, and that you be perfect in the same mind and in the same judgment” (1 Cor. 1:10). He says that Christ “gave … pastors and doctors … for the edifying of the body of Christ, until we all meet together in the unity of the faith … that henceforth we be no more children tossed to and fro by every wind of doctrine” (Eph. 4:11–14). We have already shown that this unity of faith is secured by the teaching authority of the bishops, presided over by their infallible visible head, the Bishop of Rome (Book I. Part L, and supra, p. 303 sqq.). It is a unity of faith in the whole of Revelation, and not in certain parts of it; for to reject even a single revealed doctrine is to reject the authority of God (supra, § 38). “In many things they are with me, in a few things not with me; but in those few things in which they are not with me, the many things in which they are will not profit them” (St. Augustine, In Ps. liv. n. 19).

2. A religious society having one faith must necessary also have unity of worship, which is the outward expression of the faith and social union of the members. Hence the Catholic Church throughout the world has the one same sacrifice of the Mass, and all her members participate in the same sacraments. “For we, being many, are one bread, one body, all that partake of one bread” (1 Cor. 10:17); “One Lord, one faith, one baptism” (Eph. 4:5). “Except you eat the flesh of the Son of Man and drink His blood, you shall not have life in you” (John 6:54; cf. Matt. 26:26; 1 Cor. 11:23). “All these were persevering in one mind in prayer.… And they were persevering in the doctrine of the Apostles, and in the communication of the breaking of bread and in prayers” (Acts 1:14; 2:42). “Neither attempt ye,” says St. Ignatius, “anything that seems good to your own judgment; but let there be, in the same place, one prayer, one supplication, one mind, one hope, in love and joy undefiled. There is one Jesus Christ, than whom nothing is better. Wherefore haste ye all together, as unto the temple of God, as unto one altar, as unto one Jesus Christ, Who proceeded from one Father, and is in one, and to one returned” (Ad Magnes., 7). “God is one, and Christ one, and the Church one, and the chair one, founded by the Lord’s word upon a rock. Another altar or a new priesthood, besides the one altar and the one priesthood, cannot be set up. Whosoever gathereth elsewhere, scattereth” (St. Cyprian, Ep. xl., Ad Plebem, De Quinque Presb., n. 5, and De Unitate, passim). “Adoration is necessary, but adoration which is not out of the Church, but is ordered in the very court of God. Invent not, He saith, your own courts and synagogues for Me. One is the holy court of God” (St. Basil, Hom. in Ps. xxviii. n. 3).

3. On the unity of government, necessary to preserve the unity of faith and of worship, we have already spoken when treating of the Primacy of St. Peter. See Leo XIII.’s Encycl., Satis Cognitum.

The above was taken from: Wilhelm, Joseph & Thomas B. Scannell. 1908. A Manual of Catholic Theology: Based on Scheeben’s “Dogmatik.” Third Edition, Revised. Vol. II. London: Kegan Paul, Trench, Trübner & Co. Ltd.