Unity of the Spirit

From Anstey’s Doctrinal Definitions:

This expression has to do with the practical unity that ought to exist among the members of the body of Christ (Eph. 4:3-43Endeavoring to keep the unity of the Spirit in the bond of peace. 4There is one body, and one Spirit, even as ye are called in one hope of your calling; (Ephesians 4:3‑4)). It is a unity of fellowship which the Spirit of God is forming on earth to express the truth of the “one body” (Eph. 4:44There is one body, and one Spirit, even as ye are called in one hope of your calling; (Ephesians 4:4)). F. G. Patterson said that keeping the unity of the Spirit is “to endeavour to keep in practise that which exists in fact.” Thus, God would have the members of the body of Christ to move together ecclesiologically and practically, so that the world would see a demonstration of that oneness that exists in the body of Christ—regardless of where the members of the body may be located on earth.
“The unity of the Spirit” is not merely an exhortation to have unity in a local church fellowship; it is more than that. This unity has in view the one body—as the next verse (Eph. 4:44There is one body, and one Spirit, even as ye are called in one hope of your calling; (Ephesians 4:4)) states: “for there is one body.” Since the body of Christ is not in any one locality on earth, it is clear that this is referring to a worldwide unity of believers. Thus, God intends that Christians would universally move together in fellowship, giving expression to the fact that they are one body, even though the members are in many places on earth. The act of breaking bread is a practical confession of this truth (1 Cor. 10:16-1716The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? 17For we being many are one bread, and one body: for we are all partakers of that one bread. (1 Corinthians 10:16‑17)), but the Church should also manifest the oneness of the body in practical matters of fellowship and discipline. God intends that this should be carried out on a worldwide scale—wherever the members of the body are situated on earth. This rules out the idea of local assemblies being autonomous. The Corinthian epistles emphasize this side of the truth.
Many confuse the unity of the Spirit (Eph. 4:33Endeavoring to keep the unity of the Spirit in the bond of peace. (Ephesians 4:3)) with the union of the body and the Head (1 Cor. 12:12-1312For as the body is one, and hath many members, and all the members of that one body, being many, are one body: so also is Christ. 13For by one Spirit are we all baptized into one body, whether we be Jews or Gentiles, whether we be bond or free; and have been all made to drink into one Spirit. (1 Corinthians 12:12‑13); Eph. 2:1515Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace; (Ephesians 2:15)). The former we are to keep, but the latter God keeps by the indwelling Spirit. The unity of the Spirit can be interrupted and broken. But union can never be broken. In the early days of the Church this unity was kept. The saints were all of “one accord” (Acts 2:1; 4:321And when the day of Pentecost was fully come, they were all with one accord in one place. (Acts 2:1)
32And the multitude of them that believed were of one heart and of one soul: neither said any of them that ought of the things which he possessed was his own; but they had all things common. (Acts 4:32)
), but sad to say, it didn’t remain that way for very long. C. H. Brown said, “Evidently, the unity of the Spirit must have been broken at some time, with the result that two companies go apart from each other. The unity of the Spirit must have been broken, and indeed it was” (The Ground of Gathering, p. 28). C. H. Mackintosh said, “Breaking the unity of the Spirit would be the case if we held that there were many bodies” (The Church, p. 9). J. N. Darby said, “Ananias and Sapphira were the first to interrupt it (Acts 5); after that, you find the Hellenists murmuring against the Hebrews (Acts 6).” Union, on the other hand, is intact universally, regardless of whether the members of Christ’s body walk together in practical unity or not. Union, therefore, is not the same as unity. To emphasize the difference between these, it has been said that if we tied two cats together by their tails, we would have union, but we wouldn’t have unity.
It is a sad fact that the Church has not kept the unity of the Spirit, and as a result, it has become divided in testimony. Today there are a thousand factions, sects, and fellowships—each with their own principles of government, all of which are independent of each other. Even though this is true, Christians can still keep the unity of the Spirit today, but it can only be in a remnant testimony. The unity of the Spirit finds its center in Christ, and keeping it involves being in concert with the mind of the Spirit who is leading Christians to that practical end. The members of the body must not only recognize Christ’s authority in all things, but they also must walk in holiness and truth, because the Spirit of God who gathers Christians according to the truth of God is “the Spirit of holiness” and “the Spirit of truth” (Rom. 1:44And declared to be the Son of God with power, according to the spirit of holiness, by the resurrection from the dead: (Romans 1:4); John 14:1717Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you. (John 14:17)). Thus, it necessarily involves separation from everything in doctrine and practice that is inconsistent with His Person.