It's rooted in the experience of God, and the faith that the destruction of that tiny little pistic core of doubt brings. A mystic's faith isn't challenged by doubt, it's reaffirmed by it, and grows stronger without growing harsher or more intolerant of others. These are the people who we tend to think of when we think of the positive examples of faith. Jesus, for example, was a mystic. So were the Disciples.
Saints are mystics.
So are Prophets, and the better Priests and Reverends and Rabbis and Monks. It's these people who show us the positive side of faith, and prove to us that yes, faith can be a good thing, that it is worth having, and that morals are something more than shit on your boots to be scraped off at the first chance of material gain. Anyhow, I'm rambling at this point, and I hope I made some sense somewhere along the way. I think that the search for all the answers to life the universe etc, etc etc, is so individual a quest that humanity as a whole couldn't accept it unless everyone undertook it whole-heartedly all at the same time, something very unlikely. Even then, the answers would be different for each person.