For too many Christians, vagueness is the vogue; all they have is the courage of their confusions. (Anon)

Doubters invert the metaphor and insist that they need faith as big as a mountain in order to move a mustard seed. (Webb B. Garrison)

Give me the benefit of your convictions, if you have any.  Keep your doubts to yourself; I have enough of my own. (Goethe)

Christ distinguished between doubt and unbelief.  Doubt says, “I can’t believe.” Unbelief says, “I won’t believe.”  Doubt is honest.  Unbelief is obstinate. (Henry Drummond)

There are too many who find, or think they find, a cheap ticket to scholarship in parading their doubts. (Alexander Frazer)

There is no moral power in doubt.  (Tryon Edwards)

There lives more faith in honest doubt, Believe me, than in half the creeds. (Tennyson, In Memoriam)

The wise are prone to doubt (Greek proverb)

If a man will begin with certainties, he shall end in doubts; but if he will be content to begin with doubts, he shall end in certainties. (Francis Bacon, The Advancement of Learning)

Education: to move ‘from cocksure ignorance to thoughtful uncertainty.’ (Kenneth G. Johnson)