My guiding principle is this: Guilt is never to be doubted.
— Franz Kafka

Who never doubted, never half believed. Where doubt is, there truth is -- it is her shadow.
Philip James Bailey doubted quote

The right of a nation to kill a tyrant in case of necessity can no more be doubted than to hang a robber, or kill a flea.
— John Adams

People in general are equally horrified at hearing the Christian religion doubted, and at seeing it practiced.
— Samuel Butler

To have doubted one's own first principles is the mark of a civilized man.
— doubted quotation by Oliver Wendell Holmes