Definition of "delusion" in DSM-5

[Mister Agenda]

Surely you're changing the definition here. The DSM-5 doesn't say anything about the crippling effect of the delusion.

Psychological diagnoses in general take the affect on the person's ability to live their life into account. If I think Mossad is following me but I'm cool about it and don't habitually grab people by the collar to harangue them about it, my irrational belief isn't causing any real problems. It makes me eccentric, not insane. In the case of religion, believing what you've been taught is true since you were a small child and what nearly everyone important to takes for granted is true is a learned position, not a delusion, and, arguably, adaptive. You may be better off in many senses if you continue to believe.