And, really, why am I supposed to treat religion different from other mental diseases?
Because it is not.
My mother is very religious. She attends mass every Sunday, she's a roman catholic so she believes in God, Jesus, Virgin Mary, the apostles and the saints. Yet she doesn't believe the Sun goes around the Earth, or that the Earth is the center of the Universe, or that we actually came from Adam and Eve. She's a smart, balanced, and certainly not mental diseased person. I think what you should consider a mental disease is fanaticism. Over anything. Specially religion. That's what really distortion reality for some.
The shortest distance between two points is under construction. -- Noelie Alito