What do you consider mental illness?
ADD, and ADHD are the same thing basically. OCD. By OPD I assume you mean ODD and yes these are all nothing but sin with another name. It is the Medical professions way to define why people do what they do instead of believing what the bible says. The problem is that it has crept into the church and God is no longer the authority, Doctors are. The cure is confession and forsaking, not drugs.
Would you mind defining, in detail please, what possible agregious sins a little two or three year old boy could have possibly committed in his short life that would have caused him to be stricken with ADD?
How about that little four year old girl who washes and washes her hands? Since I don't think she's read Lady Hamlet's soliloquy. "out damn spot", what horrible sin has she committed that God would send OCD her way?
Oh, and how about the person who simply loses his or her temper because someone on the Baptist Board keeps throwing stones at them? Jesus lost his temper at the money changers....did he have unconfessed sin in his life?
I am not advocating drugs as a solution to sin. Never have, never will. I do advocate drugs as a solution to illness. When I have bronchitis I use my inhaler...I'm sick. When I had the shingles I took those blue horse pills faithfully....the itch was terrible and I wanted them gone! I don't get bronchitis, or I didn't get the shingles because of sin in my life. I got them because of SIN IN THE WORLD! It's the same with other illnesses, mental to be specific. Adam fell from grace and sin entered the picture. Mankind has suffered since. We can only treat the symptoms with medication. Only God can provide the cure for sin. However, let me stress here....confessing sin will not cure someone of ADD, OCD, or anything else. God may, or may not, cure someone. It's no different than praying to be cured of cancer.