This is from A.A. Hodge:
Now, as to the unity of this Church I have something to say. A great many are agitated at present with regard to Church unity and its manifestations, and I think there is a great deal of confusion of thought as to the original conception of the Church itself. If the Church be an external society, then all deviation from that society is of the nature of schism; but if the Church be in its essence a great spiritual body, constituted by the indwelling of the Holy Ghost through all the ages and nations, uniting all to Christ, and if its external organization is only accidental and temporary, and subject to change and variation, then deviation of organization, unless touched by the spirit of schism, is not detrimental to the Church. I do believe that God’s purpose, on the contrary, has been to differentiate his Church without end. You know that the very highest form of beauty of which you can conceive, the very highest form of order, is multiplicity in unity, and unity in multiplicity; the higher the order of unity, the greater must be the multiplicity.
This is so everywhere. Go to the ocean: every drop of water is the repetition of every other drop, and there is union simply without diversity. Go to the desert of Sahara, and every grain of sand is the duplicate of every other grain of sand; but there is no unity, no life. You could not make a great cathedral by piling up simple identical rhomboids or cubes of stone. It is because you differentiate, and make every stone of a different form in order to perform a different function, and then build them up out of this multitudinous origination into the continuity and unity of the one plan or architectural idea, that you have your cathedral. You could not make a great piece of music simply by multiplying the same tone or sound. In order to obtain the harmony of a great orchestra, you get together a large number of musical instruments, or you have a great number of human voices in a choir, and you combine them; then you have an infinite variety of quality and infinite variety of tone. You combine them in the absolute unit of the one great musical idea which you seek to express.
But if this is true of such things, it is more true of Christ’s Church. If God had followed our idea, how simple a thing it would have been to make a united Church descending from Adam and Eve! We might think that was all that could be done, and there would be then no stones of stumbling. You could then watch this Church, and it would go on indefinitely and without limit.
Now, what has God been doing? He has broken humanity up into infinite varieties. This has been his method. He has been driving it into every clime. He has been driving it into every age through the succession of centuries. He has been moulding human nature under every variety of influences through all time, until he has got men in every age, every tribe, every tongue, every nation, every colour, every fashion—in order to do what? Simply to build up a variety, to build up the rich, inexhaustible variety which constitutes the beauty in unity of this great infinite Church of the first-born, whose final dwelling-place is to be in heaven.