T errible things happen in any nation where good men fall silent on critical issues facing the nation.
or
Evils that befall the world are not nearly so often caused by bad men, as they are by good men who are silent when opinions must be voiced.
or
Evil thrives because ''good men do nothing'' when faced with the need to stand up and be counted as a force for good.
Any of these close?
edited because I forgot one.