...of the moment
http://oglaf.com/acrophobia/ - man, the first 4 panels are a good stand-in for a host of prejudices.
"I don't think Osama bin Laden sent those planes to attack us because he hated our freedom. I think he did it because of our support for Israel, our ties with the Saudi family and our military bases in Saudi Arabia.
You know why I think that? Because that's what he f***ing said!
Are we a nation of 6-year-olds?"
--David Cross in 2004.
By similar reasoning, the Charleston shooting was not hating "Christianity", it was about hating black people.
You really can take some forms of hate at face value. Similarly, it's often not "utterly irrational", but a dumb kind of logic starting with horrific, wrong, and evil beginning assumptions.
Of course, the follow up logic is often lacking. "Uh, this is going to start a big race war! Hooray!" Hint to all future massacre planners: so very, very few people will find your murder of innocents inspiring, and the ones who do, you really don't want on your side.
Of course, the fact that the Treyvon Martin case was an inspiration as well. "Hey maybe I can get on this too" seems to be the pragmatic takeaway.