Because they share views on important issues that affect their community or country. It doesn't matter what kind of view they hold, whether it's positive or negative; whether they agree with another group's views or not. So groups like clubs or organizations are called "like-minded" because they have things in common. They all enjoy playing tennis, for example, so they're likely to have many other things in common. Even though there may be people who don't get along with others within the group, they still consider themselves part of it.