If you're consciousness convinced about something -which is not the same that "
being convinced that you are right"- you are not illness, that's right.
That's what the doctrine/teaching says.
I'll ask you this.
Were Romans -from the Roman Empire, or Greeks- suffering from some kind of mental illnes when they
slept with teens -Plato and Aristotle e.g. (an widespread practise )-?
Absolutly not, there is such a big bibiography about that.
They just had a different moral code, but today they'd be called pedophiles.
Exactly the same that Islamic fundamentalists. Do I like them? Of course not. But one thing is in what we believe and another is how our brain works and what Science says about that.
Read this,
Historian's fallacy.
I'm assuming you're Christian, like me, were our ancestors
crazy (had some kind of mental illness) when they went to the Crusades? Which were just a Holly War like the Islamic Fundamentalism today... No. Now read the links I posted.
And again, what a Mental Illness, according to Science, is,
A mental disorder or psychiatric disorder is a psychological pattern or anomaly, potentially reflected in behavior, that is generally associated with distress or disability, and which is not considered part of normal development in a person's culture. Mental disorders are generally defined by a combination of how a person feels, acts, thinks or perceives. This may be associated with particular regions or functions of the brain or rest of the nervous system, often in a social context.
EDIT: I think there's a better example about that.
Think in the abortion. And in two people. One's a Tea Party follower and the other one is a communist or a democrat -I'm not saying that democrats are communists-.
For the Tea Party folower the abortion is a crime, an assasination. The democrat will think is just an option. Now extrapolate it to the Religious Fundamentalist and our Occidental culture.
Same think with the Death Penalty. For us Europeans -for the most of us- it's a crime (and I don't want to criticize anyone). For some Americans is the most normal and fair thing.
Who's right and who's wrong? It depends on the point of view and the cultural environment. And in the three cases (fundamentalism, abortion and death penalty). There's a side thinking than the other one is killing a human being and the other one is thinking that is doing the right thing to do.