(As DADVocate pointed out.)
It used to be the Irish.
It has been so many groups of people in the past (and present), you start to wonder why we have to go over this lesson again and again. As someone whose family is majority Irish-Catholic, though, it behooves me to place myself in the shoes of centuries gone by. While discrimination and persecution haven't come for me because of my ethnicity or religion, I know I have only to thank the timing of my birth.
The thing that gives me the most hope after reading about how disgusting some Americans can be is that we've been through all this before.
Hell, we're still going through it now.
The process is very, very messy.
And sometimes it takes a very, very long time to get over things. Which is why it is important for those of us who believe in the freedom of religion and the promise of America to say something now.