You could point out all the atrocities perpetrated by non-whites, and yet they will still tell you that the sins of whites are far more egregious than those of other races.
I pointed out the Mongols slaughtering of millions of Europeans and Asians, the Turks and the Moors invading Europe and killing millions, and the Arabs taking millions of Europeans as slaves. I also mentioned all the plagues and diseases coming from outside Europe that killed millions of Europeans. I received no reply.