Whether Hitler or Pol Pot or Saddam Hussein there is no requirement to hate them or to in your heart condemn them. Certainly it is understandable - but it is unneccessary. God will take care of eternal Justice. The Iraqis will likely hang Saddam. Hitler apparently killed himself.
We have government to incarcerate those who break the law. Our business is to love God and love one another. That does not mean that we are not actively engaged in life and in interacting with others and in trying to set an example or in trying to persuade others in that which we believe is good and true. But it is not necessary to be cruel or punitive or hurtful in the normal actions of living our lives. Surely we can be better than that!