You got that backwards, when you make a claim which in your opinion is representative of a given fraction of a population the onus is on you to prove that it actually does represent these people, not on those who cast doubt on your agency for the group.

Also, most of my reply was a direct quote from Martin Luther King's famous speech. The rest of the reply is a statement of fact on the cultist nature of the concept of 'white guilt'. Please explain to me in what way this sounds like a white supremacist diatribe, as far as I understand white supremacists are not wont to cast aspersion on their 'white brethren'.

Stop throwing these labels around, they can not replace rational arguments and are just a form of academic laziness.