I remember an old story. In India, taking wine is considered very bad. There were two brothers who wished, one night, to drink wine secretly; and their uncle, who was a very orthodox man, was sleeping in a room quite close to theirs.
So, before they began to drink, they said to each other, ‘We must be very silent, or uncle will wake up.’
When they were drinking, they continued repeating to each other ‘Silence! Uncle will wake up’, each trying to shout the other down. And, as the shouting increased, the uncle woke up, came into the room, and discovered the whole thing.
Now, we all shout like these drunken men, ‘Universal brotherhood! We are all equal, therefore let us make a sect.’ As soon as you make a sect you protest against equality, and equality is no more. Mohammedans talk of universal brotherhood, but what comes out of that in reality? Why, anybody who is not a Mohammedan will not be admitted into the brotherhood; he will more likely have his throat cut. Christians talk of universal brotherhood; but anyone who is not a Christian must go to that place where he will be eternally barbecued.
Source: The Complete Works of Swami Vivekananda/Volume 2/Practical Vedanta and other lectures/The Ideal of a Universal Religion