Anyone who has been in a relationship knows that the opposite of love is not hate - it is indifference. So how did hate get such a bad rap as the "anti-love"? Shouldn't indifference be the subject of our denigration as being the furthest from love? It seems clear that love and hate are two different expressions of a common idea. When one is passionate about something, they either love it or they hate it.
Cognitive psychologists tell us that emotion follows cognition. In other words, first we have a thought, then we have a feeling. So therefore, hate (or any feeling for that matter) can't be good or bad - it just is. This is all common sense. We don't go about our daily lives choosing how we feel. If that were so, then sadness and pain would be absent from the world. So if I hate Mohammed Atta (which I do), am I a bad person? Can I help how I feel? Can I change my hate for him anymore than I can change my love for my family? You see, it's not emotions that determine what kind of people we are, it's the thoughts behind those emotions that determine what kind of people we are. We love what deem most important to us, and we hate that which threatens those things. Anyone who claims not to hate is either indifferent to everything, or loves nothing (or is lying to themselves).
What about women who fall in love with cruel murderers who are in prison for life? Is that love good? Would you recommend it to your daughters? Would anyone who truly values human life love someone who brutally disregards it? Certainly that love can only come from someone who cares nothing for the lives of others . It is a love that is borne of a selfish narccicistic value system that states: "My emotional and physical gratification is more important than the lives of innocent people". Only a person who has that thought, that value system, could form an emotional attatchment to a cruel killer.Do you hate suffering, or injustice, or oppression, or poverty? Would you ever say that hatred of suffering is bad? Would you ever say that the hatred of suffering can not stop suffering? Obviously no one would say that because nothing would ever be done to alleviate suffering if we remained indifferent to it. The very first step in alleviating suffering is the hatred of suffering. And as for those who would say: "I only hate suffering, not the people who cause it" I would say that this argument only makes sense if you believe that people are not the cause of their own actions (another christian idea - evil is the devil's doing). But certainly we are the cause of our own actions; you can not separate the suffering from the one who caused it. And for anyone who disagrees with that I would recommend that you tell it to the judge in traffic court, and you will soon find out that he (or she) believes otherwise.
So to answer the original objection "The hate of someone like Atta can not be stopped by more hate" makes no sense to me. People like Atta will never be stopped unless we are passionate enough about the value of human life to feel hatred for the one who wishes to destroy it.