Comment 1 by road_runner321

I prefer questions to outright statements, but try to phrase the questions as a means to gather information rather than sounding like you doubt the person's point of view, even though you may. Be amiable, but don't let the conversation be sidetracked.

Questions provide them with an outlet for voicing their faith to an attentive listener, while allowing you to learn new things by which you can gauge the limits of their understanding, and bringing them up short on inconsistencies. I believe this is called "Socratic irony", using questions, asked perhaps from feigned ignorance, to cause another person to realize something or to insinuate a point. It also involves a degree of self-deprecation or mild flattery to cause the other person to drop his guard somewhat. If you get good enough you can use the questions to steer the conversation into any topic of contention you desire.

If you want videos, I would suggest old Columbo episodes where he is questioning suspects. Perhaps you'll want to scale it back a bit for regular conversations.

This technique of asking questions from feigned ignorance (or innocence) sounds very much like the technique used by Louis Theroux in his excellent documentaries investigating extreme or weird lifestyles. Recommended viewing.