The same mindset led to the shameful internment of Japanese Americans in WWII.  To signs in Alaska that read "No dogs, no Natives".  To the signs that read, "No Irish need apply".  To the hanging of Quakers in Boston in the 1600s.  To the lynching of African Americans in the South.  To the Virginia Colony banning Catholics.  

"First they came for the Socialists, and I did not speak out—
Because I was not a Socialist. 
Then they came for the Trade Unionists, and I did not speak out— 
Because I was not a Trade Unionist. 
Then they came for the Jews, and I did not speak out— 
Because I was not a Jew. 
Then they came for me—and there was no one left to speak for me."
Martin Niemöller