The thing is, people use words as code. He says "muslim" but he means middle eastern. It's like when people here say "immigrants" they don't usually mean the ones from England and new zealand. When americans talk about "hip hop culture" they mean african americans, even though most people who listen to hip-hop are white.

Now that doesn't mean it's ok to assume that's what people mean when they say "muslim", "immigrant" etc, you have to look at how the words are being used and point out the subtext.

Also, while atheists are obviously going to have a lower opinion of religious people than of ourselves, I strongly disagree that we are justified in thinking they're all crazy, since most of the world (and any given country) is religious and no more crazy (on average) than we are. We can think they're wrong/deluded etc about that one thing but that's different from dismissing them and their opinions in general. And since most religious people are, quite obviously, not insanely violent, dismissing an insanely violent persons actions as "just the inevitable result of religion" is nonsensical.