Why aren't Christians allowed to be offended by Islam?

There is nothing wrong or scary with being politically correct, I don't understand why some people are scared of it. Being correct is meaning to take the bias out. You are allowed to be 'offended' by another religion, even though you probably wouldn't like it if they were offended by yours. Mainly because now Muslims are becoming a target for hatred now. I don't like either of your or their religions, but then again you must respect other peoples beliefs.