If someone wants to not associate with people of other ethnic backgrounds that is his or her business. If they want to marry only with in a very small gene pool I will not force them to do otherwise.
How would their doing that effect you?
"How would their doing that effect you?"
Now we're getting somewhere. The notion that murder and subjugation, in Nazism and Communism, were somehow the purview of an isolated set of fanatics is the falsehood in the original analogy. Murder and subjugation, when directed at me, will affect me greatly, perhaps to the point that there would be no "me" to engage in tit-for-tat rationalizations on internet message boards.
And now, let's go full circle, back to Islam, shall we?