This is a good short paper on how to respond helpfully to people's strange or unusual beliefs that they may tell you about. This is developed for mental health professionals, but is valuable for family members and anyone who deals with people who may have psychosis:
Responding therapeutically to disturbing beliefs http://www.testandcalc.com/voices/resources/Responding%20to%20disturbing%20beliefs%20-%20handout.pdf
This is quite useful to give me some ideas for responses when my son is highly upset by his delusions and texting me.
I missed this when it was originally posted - glad it got bumped to the top!
I have been using the suggestions - so nice to have new ways to say things.