The climax of Brave New World occurs in the final chapter when Mustapha Mond's scientific or sociological experiment with John the Savage comes to an end which, in Mond's mind and in the minds of his citizens, confirms their World State way of life. That way of life is in the mantra: Community, Identity, Stability. Identity comes from community. Therefore the World State policy is, if identity were to come from the individual, society would not be stable.
John represents the individual; he doesn't conform to either society. He realizes that he cannot abide by the lifestyles of the Reservation nor the World State. In his last moments, his self-torture continues as a way to purge himself (mentally and physically) of his lustful thoughts and perhaps even as a frustrated way to attack his own human passions which the World State condemns. John is caught between two worlds, neither of which he fits into.
John submits to an orgy, a World State pacifier, and he does this out of frustration and hopelessness. Completing Mond's experiment, John kills himself. John's violent and erratic behavior, although quite understandable and quite human, look like a circus side show to the citizens of the World State. They cheer on his behavior, thus cheering on his own demise. Mond believes John's fatal end will serve as an example that individual thinking (John) leads to complete instability and self-destruction; thus, it reaffirms the World State's policy of suppressing individual thinking.