I. Consider the unity or oneness of the Church as set forth by the unity or oneness of the body. "The body is one," says the Apostle. Notwithstanding the several limbs of which it is composed, one life animates the whole. The parts mutually subserve one another. They instinctively feel that they belong to one another; that they owe to one another mutual help and support. And so, too, the Church is one one mystical body, as we call it having one Author, which is God, and one Head, which is Christ, and one informing Spirit, which is the Holy Ghost; having one country toward which all its members are travelling, which is heaven, one code of instructions to guide them thither, which is the word of God, one and the same band of enemies seeking to bar their passage, which are the world, the flesh, and the devil; having the same effectual assistances in the shape of sacraments and other means of grace to enable them to overcome these enemies, and of God's good favour to attain the land of their rest.
II. But, secondly, as in the human body there is unity, so there is also variety, diversity, multiplicity, or whatever else we may please to call it. The Church is most truly a body in this sense also: that its different members have different functions to perform, all these being assigned to them by God; and then, and then only, it makes equable and harmonious growth.
III. Consider the lessons which we may derive from these truths. (1) We are members of a body. Let us never forget this. It is only too easy to do so. Do not let us yield to the temptation which would lead us to separate ourselves, if not wholly, yet in part, from the body of Christ, and to set up a selfish independent life of our own. (2) If we are thus members one of another, many are the debts which as such we owe the one to the other. We owe each other truth, love, honour. Let us ask of God a tenderer, livelier, more earnest sense of the sorrows, needs, perplexities, distresses, fears, trials, of our brethren.
R. C. Trench, Westminster and Other Sermons,p. 152.
References: Ephesians 4:4. J. G. Rogers, Christian World Pulpit,vol. iv., p. 380; Preacher's Monthly,vol. iv., p. 211.