Sorry, but I find that just not great discussion skill. WHY on earth would anyone tell you that they'd doubt their beliefs?
I do a lot belief work (my teacher is a guy who invented a process for people to see that their beliefs are only one truth and not necessarily THE truth). Even people who go to an expert, and pay lots of money for the privilege, don't want to doubt their beliefs. 'But it's a fact,' they cry. It's worse when they 'know' it's not a fact. And yet they can still un-believe. That's why he's my teacher. It's some of the best magick I've ever uncovered.
Anyway, I talk to people a lot about beliefs. My dad is a serious skeptic, and extra so when I bring it home. But I share my process with him, and he's witnessed me unbelieving some things the last few years. One thing he said to me was 'beliefs are the things that don't change, when everything else does.' So, he's got a belief that you can't really unbelieve things. (which is a belief that can be worked through, lotsa folks have it.
Anyhow, I've strayed a bit. You cannot approach a debate, or a discussion, by saying, 'how can I make you see you're wrong?' (which is a translation of 'is there any evidence that could make you doubt your beliefs?') If I'm approached with that, I'm likely to hear that you already think I'm wrong and you want to take away something that I not only see as valuable, but a very foundation of my very existence. Why would I offer you an opening to take that away?
Now, you show some appreciation for WHO I AM (which i think is my beliefs), and some care for how I live my life, then I am more likely to engage in conversation with you at all. Then I'm more likely to consider questions you ask me. Small questions. How about 'tell me about how going to church makes you feel, sweetie'? Which isn't really a question so much as an opening to a dialogue.
Love is that condition in which the happiness of another person is essential to your own...
Robert A. Heinlein
Me: female, bi, (formerly hinge of a vee)
with FirstBoyFriend (FBF)(moderately long-distance)
and no longer with CurrentBoyFriend (CBF)(who now lives in a house far away-with stairs I can't climb)