Doubt

Doubt is a fork in the road. Making a wrong turn can lead down a dark path where the traveler becomes increasingly disoriented and lost. 

But sometimes doubt is the right turn. For instance, if you were born Hindu, Buddhist, Muslim, Mormon, Catholic, or atheist, doubting your childhood indoctrination is a necessary step to discovering something better. You didn't start out on the right path and lose your way. You started out lost. In that situation, doubt can be a pathway out of your lost condition.

Or even if you had a good Christian upbringing, you can't leech off the faith of your parents indefinitely. You need to develop a personal conviction. In that case, doubt can be a dark path that opens out onto a sunny glen. 

If, when you come to a fork in the road, you choose the wrong road, that isn't fatal. Life is a series of forks in the road. If you take a wrong turn, there's usually a fork in the road further down the street where you can resume going in the right direction.