I believe that every Christian ought to be joined to some visible church; that is his plain duty, according to the Scriptures. God’s people are not dogs, else they might go about one by one; but they are sheep, and therefore they should be in flocks. If I meet a man, all by himself, snapping at everybody,—I may be called uncharitable, but, I should hardly think that he was a sheep, I should be afraid that he was a dog. But when I see a man who consorts with his fellow-men, feeds with them, takes delight in their company, and with them draws near to the Great Shepherd of souls, I say to myself, “I think he must be one of the sheep, for that is the way in which that animal always acts.” So, beloved, you should go in flocks or companies; that is to say, you should be joined to some Christian church.
—Charles H. Spurgeon
“The Head And The Body,” in The Metropolitan Tabernacle (Banner of Truth Trust, 1876), sermon 2653.