Exactly!
Im sorry but the whole nation of brazil does not experience what Avatar experiences, this is a misleading opinion you are posting. Maybe you are talking about the spiritualist traditions such as umbanda and candomble? If so, then know that they are a minority in Brazil. Most brazilians are catholics, and this whole 'being possesed' story is not a part of the general belief system.
Most people here that I have met (the 'common' person) are actually pretty disconnected and generally skeptical of the 'spirit' world, even though funnily enough there seems to be quite some supersticious thoughts around (specially when its about what to do so that the football team wins
).
I think you should be careful offering such opinions. Nobody of us, even the health-related professionals, can make diagnostic over a couple of posts from someone on the internet, as our Health and Safety section clearly states. Also you cannot generalize his experience to what "many people around the world share", you just cant know if its the same or not (and as I said at least in the example of Brazil, its not true the whole country feels the same or even the majority of people). And even if whole countries believed so, its still a falacious appeal-to-belief kind of argument. Just because many people believe something doesnt make it more true or right or valid or of benefit.
What if he does have a serious mental issue (im not saying he does, but just consider the possibility for the moment), and you offer such advice and he avoids health treatment and then his situation worsens and maybe he puts himself and others at risk? Then what? I think if you want to say something like that, you should at least add a very clear disclaimer before doing so (I do realise you mentioned at the end of the post he should seek a health professional if he continues feeling confused but still, I want to reinforce the idea of safety here and of being careful with advices we give).
That being said, I think you said some reasonable and interesting things about how he could reconsider his negative spin to the situation and the fear-based relationship, and rather instead try to learn from it, try to deal with it more positively, integrate the experience.