QE, I will keep him and your entire family in my prayers.
I can't imagine how hard that must be. My former pastor and his wife have a son who is pretty much just like you described your brother. He was raised right, and no matter how much fasting and prayer has been done for him-- it seems like all hope is lost.

Just keep hanging on, knowing that God has seen every tear you have shed-- and he's heard every prayer you have prayed. Sometimes he just chooses to answer in his own time, not our time. Don't give up. It's not too late to see a change.
Love ya sis...