That's a great question.
The challenge here is that ideology and identity become intertwined. When we attack someone's ideology, we're also attacking their identity and all the defence mechanisms come up. They either lash out or shut down. How do you get through that?
In Life After Hate, there's a saying we have that is “never concede, never condemn”. People ask me what they say to their uncle or to Aunt Maggie who's spouting off all this nonsense. I ask them if they want to be right or if they want to effect change. If they want to be right, just tell Aunt Maggie all the reasons why she's wrong. If they want to effect change, listen. It's not about what they say, it's about what they do.
It's that tension between never conceding your values, but never condemning the person. The ideology and the activity is abhorrent, but it's still a human being. It's that tension of never concede and never condemn.
For facts, figures and counter-narratives, there is a place for that for someone who's just coming across this type of information. That's an effective place to deploy that, just not on the back end.