Doubt and Fear

The Hawkins book I am reading quotes Emily Dickinson. She says that "we both believe and disbelieve a hundred times an hour, and that keeps believing nimble."

Is there a benefit to doubt? It seems to me that the movement between disbelieving and believing would be like the stretching of a muscle, and that it would strengthen faith. Questioning, exploring, reaching, pulling away and coming back -- it would keep faith nimble, as Dickinson says. Doubt can result in growth.

Could it be that when someone believes we should not question God and that to doubt faith is just wrong is afraid that God will not be strong enough to withstand the testing? Could we step away from doubt out of fear?