Okay this is not gonna go over well, but, that's never really stopped me before. [Actually, social disapproval is one of the ways that our minds become colonized, circumscribed, and constrained. And it is only through risking social disapproval that we break through those chains to see the world as it really is.] So here goes:
By any standard modern definition of mental health, the founders of most of the major world religions were mentally ill. Matching our modern understanding of mental health up against the written accounts of the actions of these religious figures, one would observe that:
Siddhārtha Gautama, the Buddha, appears to have suffered from anti-social personality disorder. He abandoned his family and avoided most personal relationships with other people, preferring instead to live under a tree with his eyes closed for most of his life.
Abraham, the patriarch of the Israelites and the Jewish faith, appears to have suffered from paranoid schizophrenia: he heard voices, thought God was talking to him, and tried to murder his own son because of the voices in his head.
Jesus of Nazareth, the founder of the Christian faith, appears to have suffered from narcissistic personality disorder. He thought he was the son of God, told people to abandon their families, give everything away, and follow him.
I know less about the life and works of Muhammad ibn ‘Abdullāh, the founder of Islam. But he too, claimed that angels sent by God spoke directly to him and is said to have transcribed an entire book, the Qur'an, based on these messages from God. Today we would call that sort of thinking schizophrenic.
Martin Luther (who started the Protestant Reformation), St. Ignacius of Loyola (founder of the Jesuits), and John Bunyan (author of Pilgrim's Progress which formed the cornerstone of Puritanism) all suffered from obsessive compulsive disorder.
Joseph Smith Jr., founder of Mormonism, was a well known con man. [Read Jon Krakauer's book, Under the Banner of Heaven to learn more.] I don't know where being a con man fits in the DSM-IV but needless to say, it suggests that Smith's mental health was not 100%.
What this suggests is that 1) our tradition of holding the medical practice of psychiatry in high esteem; and 2) our tradition of respecting various religious traditions -- are fundamentally incompatible with each other. To the extent that we hold that the DSM-IV is the best approximation we have for what constitutes mental health and mental illness -- then we necessarily conclude that the followers of the various major religions traditions are following the teachings of people who were likely suffering from mental illness. And to the extent that we conclude that religion is a good and true depiction of life on earth (and beyond) -- then we necessarily conclude that the DSM-IV is invalid. And yet, most respectable, modern people in Western society hold these two fundamentally incompatible sets of views ('religious tolerance is good and modern psychology is good') without noting the severe dissonance between these two sets of views.
Said simply -- it seems that we either we need to respect crazy people more, or respect religious traditions less.