I'm new here and didn't know if this has been a topic of discussion yet, but I found this story to be fascinating:
In short, two psychologists modeled decision-making in a variation of the Prisoner's Dilemma with a "quantum" probability model. Their motivation was to reconcile results from actual studies (the participants consistently made apparently irrational choices) with what classical probability theory predicts a rational agent would choose.
Oh, and the quantum thing isn't new-age mysticism at all. It'...
I had a similar discussion with a family member, about the existence of the Christian god, where I received that exact response. My wife was sitting right there. I responded with something along the lines of, "True, but my 'faith' in her love is already backed up by evidence, and besides, I have plenty of evidence that she exists. If there was evidence for God and evidence of His love, I would happily put faith in that too."
But I agree - it definitely caused me to pause to consider a tactful response.