All that is necessary for the triumph of evil is for good men to do nothing.
By Edmund Burke
What does all that is necessary for evil to triumph is good for men to do nothing mean?
Actually, the quote is, "All that is necessary for evil to triumph is for good men to do nothing." Perhaps getting the order of the words correct helps with the meaning. It often does so in the English language, unlike some other languages where it sometimes makes little difference. The above quote is attributed to Edmund Burke, a well-known 18th century political philosopher. It has been quoted often in recent years, especially by reform candidates for public office, sometimes without appropriate attribution.
It means that evil is not neutral; if you and/or society stop resisting evil, it will continue to grow and spread. It is a call to arms for people to stop being complacent.
Evil is not neutral and there can be no neutrality exercised toward it. Anyone who is not against it is perforce in favor of it.