Faith

"You never know how much you really believe anything until its truth or falsehood becomes a matter of life and death to you.  It is easy to believe a rope to be strong and sound as long as you are merely using it to tie a box.  But suppose you had to hang by that rope over a precipice.  Wouldn't you then first discover how much you really tested it?... Only a real risk tests the reality of a belief."  ~C.S. Lewis