So, being not normal is now the set point for mental illness? Are people with cancer mentally ill too? They aren't normal. How about people with psoriasis, Downs syndrome, or aposthia?
Maybe we should consider adults who believe in a fictional higher power mentally ill. We grow out of our beliefs in fictional things like Santa Claus, the Easter bunny, and the tooth fairy. Maybe the inability to grow out of the belief there is some sort of higher power is a sign of mental illness. People who believe in god have some pretty irrational thoughts, probably more so than a man who feels like he's a woman.