Be skeptical when appropriate,
have faith when doubt can be eliminated.
When the Buddha warned us about doubt (one of the five poisons, the others being greed, anger, ignorance, arrogance), he was not talking about reasonable skepticism in daily matters. For example, questioning how an investment could possibly double our money in three years.
The Buddha was speaking of doubt in the sages’ teachings.For us, it is doubt in the Dharma.
Based on our roots from previous lifetimes, we come to the teachings with varying degrees of doubt. We whittle away our doubt by experiencing the truth of the Dharma and thus verifying it for ourselves.
For instance, we experience that, yes, when we live a moral life we worry less. Chiseling away at our doubt, we will reach the point where we accept certain teachings on faith.
An example? Once born in the Pure Land, we will attain enlightenment far more quickly than with other methods. When the teachings and our experience mesh, we will let go of our hesitation. And our doubt.