The point is, you have to realize that when you sing songs of a political nature you are going to alienate and/or hurt the feelings of people who believe the opposite.

Another point is that most protest songs are protesting some form of repression -- economic, political, social, military, racial. Of course the people who are doing the repressing are going to be put off by the music. Boo hoo.

In the example given, anyone who is a war monger and supports wholesale killing should expect to get grief for it, even if they have somehow convinced themselves that it's a noble endeavor.