Malcolm Muggeridge once said, "To believe greatly, it is necessary to doubt greatly." If we believe in God greatly, it's necessary to develop a healthy skepticism toward all that smacks of untruth or deception.
Doubt keeps faith active. It keeps us from settling on what is unworthy of it. "Hate what is wrong," wrote Paul. "Hold tightly to what is good" (Rom. 12:9).
As believers we must become great doubters of all things false if we are to be true lovers of the truth.