If you're not bothered about the outcome, just say there's some stuff you don't agree with, if he presses you then pick a subject you're confident to talk about. You may help him. Mist likely you'll just scare him off, but worth a try if you don't mind not seeing him/them anymore.
I'm presuming you're not baptised. I've just realised this is a big presumption. Ignore me, others will give good advice!