My immediate reaction is that it must be in the eye of the beholder. In other words, to the atheist who considers God to be a “delusion” any practicing religious person could fit that clinical definition.
And yeah, it goes for atheists too. Michael Newdow who sued about God in the pledge, would be diagnosed the same way. Actions which are social inappropriate to satisfy one's own needs, fall into the OCD diagnosis.
And could cross to Borderline Personality Disorder or Narcissistic Personality Disorder, but I would need more information from the DSM-IV