Albert Einstein once said; "the world will not be destroyed by evil people, but by good people who do nothing when evil is being done by them"
Which is true, as prophet Muhammad (peace be upon him) has said similar thing, which is
"Whosoever of you sees an evil action, let him change it with his hand; and if he is not able to do so, then with his tongue; and if he is not able to do so, then with his heart; and that is the weakest of faith."