Does a narcissistic person usually think they are God?

No. Narcissus was a greek tragic character who fell in love with himself. Narcissism, as a result, means someone who thinks far too highly of themself, placing theimselves above the needs of others. It's vanity taken to it's most extreme form. Think Hugh Grant's character in the Bridget Jones movies. It's more of a social defect than a mental illness. On the other hand, someone who truly believes themselves to be a god may well be suffering from delusions. This is indicative of serious mental health concerns. Of course, one of the side effects of such a delusion may well be elements of narcissistic behaviour. Hope this helps :) The ones I know. Think they are the center of the universe. Everyone and everything revolves around them. This is why they are aethiest. They can't belive there might be a higher power, whether it be God, mother-nature, or anything.