I ranted once at my fundie mother about how and why taking the Bible literally constituted deliberate misreading of it and that this was evidence of bad and unclear thinking and was therefore an error of religion. I'm not sure if she was convinced at all, but she's sure never brought up religion with me since. Note that I am in no way a Christian, in fact being completely atheist. I am still unsure if this constituted dark arts. I did, however, intend it to be a seed of the notion that joined-up thinking is not optional.

I have considered the possibility of my strategy backfiring, so I try to choose something I know they would be (relatively) certain to not accept, which also has simple ways you can show it is irrational, and something I do not actually believe (so I do not need to go back and tell them why my original opinion was probably correct after all later on) The Santa clause example might work if you were joking with a friend, but if you are in a more serious situation, something which is less obviously a trap would work better.

So far, I have not knowingly convinced anyone I know to accept an insane idea, but it is still something to watch out for.