People get offended by things whether you like it or not. It's extreme to make death threats, but it's also extreme and fairly despicable to go out of your way to offend an entire group of people simply because a subset of those people are acting extremely. If someone punches me in the face for making lewd comments about his mother, is it constructive to then go around making lewd comments about anyone's mother who thinks that these comments are offensive? I think the organizers of this event are free to do what they want, but it's still a pretty tasteless thing to do. And if people take this as a reflection on all atheists, it DOES make us all look bad.