“You should never, never doubt something that no one is sure of.”

“Oh! let us never, never doubt
What nobody is sure about!”

“Why is doubt the one thing we're never skeptical of? We question other peoples' beliefs, and the more sure they are the more we doubt them. But it never occurs to us to doubt our own doubt. Question our own questions. We think our questions are answers.”

“Scientists should never claim that something is absolutely true. You should never claim perfect, or total, or 100% because you never ever get there.”

“When you’re young you never doubt yourself. You never wonder if you’re justified. But as a man gets older he learns to doubt. Whether he can do a thing—whether he should.”

“Faith doesn't mean you never doubt. It only means you never act upon your doubts.”

“Never reveal all of yourself to other people; hold back something in reserve so that people are never quite sure if they really know you.”

“Looks, doubts, kisses and hugs should never be left pending.”

“Frantic orthodoxy is never rooted in faith but in doubt. It is when we are unsure that we are doubly sure.”

“Christianity is a life, not a doctrine… I'm not saying never doubt or question. The Lord gave you a mind so that you would make honest use of it. I'm saying you must be sure that the doubts and questions are your own.”