One of the main problem with most political groups, is that many, of their members will be very open-minded when it's convenient, but extremely close-minded when it goes against their PoV.
That's why, in a debate, nobody is trying to make the "other side" change their mind, it's not ever gonna happen, because both sides are absolutely convinced to be 100% right. Instead both sides are trying to convince the people listening to them that they're right.
In your case, trying to approach a political group with diverging opinions, no matter how many fact, studies, and numbers you bring with you, it won't change their view. You're simply going to engage 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.
Edit, in views of informations in comments
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 :
- 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).
- How it would affect your relationship with them (if you have a significant relationship with them, such as a Romantic relationship, or a Friendship).
- 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.