In politics, when a "group" grows, it tends to attract more and more people, those people come with their own views and take on the general idea represented by the "group".

For exemple, Feminism is about fighting the inequalities met by women in society, as to make them 100% equal to men. But, since Feminism is so massive in number, there is many, many subsets, and every subset have their own idea of what *"fighting the inequalities met by women in society"* means, and how they should go about it. Some subsets think that both men, and women are targets of inequalities, and unfair treatment. While other subsets think that men are innately sexist, and are the ennemy of women in general.

The more a group grows, the more likely it is to contains at least some extremist subset. Those subset usually harbor a more hateful community, sadly, those community tends to be the most active, depicting a less than likeable idea of any group, to stay in the Feminism example, today, to stereotype of a feminist is a man-hating woman.

In your case, confronting the group about their ideas, and how it makes them look to the outsiders eye won't help. It will either lead in you being dismissed, or in a fruitless debate.

If you want to help your friend, confronting that group is not gonna help, what you should do is talk to this person, and this person only, and try to reason with them. If they're not too politically oriented, they might listen to what you have to say. Don't forget that if they decide that they don't want to listen to you, there's not much you can do. 

The only way anyone decide to change their political views, is not when they're confronted about it, but when they decide to do so.

If you decide to ask them to pick another group, and assuming they care enough about you, I would suggest you to be honest about the reason *why* you want them to pick another another group. And how the ideas in the group they're currently in *affects you*.

Somthing along the lines of : 

> I know you really care about feminism, and I understand fully, but some of the ideas of this group are quite hateful, and biased toward other groups. If you started believing in those idea, and/or acting on them, I would feel terrible for X/Y reasons.

>Could you maybe see if another group would not suit you better ?

This way you don't accuse them of condoning, agreeing, or buying into those ideas, you simply tell them how you feel, and what you're afraid of.

As for the reasons as to why it would make you feel terrible, try to be honest, and rational :

 1. Hateful ideas depict a wrong image of any groups, and lessens any message and/or voice they could/would have otherwise. (No matter how great, or right your ideas are, if you spit on another group, they won't want to join you).
 2. How it would affect your relationship with them (if you have a significant relationship with them, such as a Romantic relationship, or a Friendship).
 3. How those ideas makes you, as a person feel. (again, only if the other person cares about you).

 **But always remember that, ultimately, it's going to be their choice, and theirs only.**