I disagree with your interpretation of riverman's initial post. I think it is possible to make reference to an individual's religion--even in a derogatory fashion--without that reference being derogatory to the entire religion or all adherent's thereto.
For example, if someone suggested that a "Christian" neo-nazi domestic terrorist should be tattooed with a star of David and a "666" before being executed, I wouldn't take that as a referendum on all Christians, but as a desire for that particular person to suffer a fate that he would consider an ultimate indignity. I viewed riverman's post in the same light.