I am a little concerned that you refer to a psychiatrist as a "shrink". Some of the things such as that that people say can actually be quite hurtful to the ill person or his family using such a term really carries quite a negative connotation, if you want to help your brother, I would suggest changing your vocabulary. Use psychiatrist, doctor, counselor, whatever is appropriate and correct. Shrink seems to have gotten it's start as a shortened version of headshrinker. It seems to me to be a bit of a contradiction if you are saying your brother is demon possessed he should see a headshrinker! Just a comment on vocabulary, and I don't mean it to be that you say it to be hurtful, but how it is meant and received can be very different and families struggling with these problems can be very sensistive and I wouldn't want your sincere desire to help be turned into hurt just by your use of slang terms.
Your friend says he is demon possessed and you seem to just accept that. What if he said you were a demon or demon possessed too? Would you just accept that as well? The point is, don't take what comes out of his mouth as the truth, it is not trustworthy.
I would encourage you to talk to your pastor about the situation, its really something best faced by the whole congregation as a family together. Maybe his blood family needs some financial aid. Certainly prayer is needed. Maybe this is an opportunity to reach out to others in the congregation also suffering from mental illness yet afraid to let it be known because of what they think people will think. Often, people are quite afraid to talk about any mental problems. There has been and in many cases still is quite a stigma connected with mental illness. That shouldn't be because it increases the damage the illness causes.
Thanks for the comment regarding the shrink. I had no idea the connotation was bad. Don't worry, I wouldn't offend him or the family because they don't speak english that well. We have another term used for psychiatrist and it is respectful.
And also, don't worry I dont accept that he is demon possessed. I already explained to him that light can not exist with light and that the Christian's body is a temple for the holy spirit and satan cannot possess it. AMEN!
We currently don't have a pastor, but our whole youth group does go visit and pray for him.