Robert Frost contemplates this debate of the force of Love vs. Hate in his poem "Fire and Ice":
Some say the world will end in fire,Some say in ice.From what I’ve tasted of desireI hold with those who favor fire.But if it had to perish twice,I think I know enough of hateTo say that for destruction iceIs also greatAnd would suffice.
While this is a topic that has been debated through out the centuries, I think that one of the most important elements of this argument (which is often overlooked) is the power of forgiveness. Forgiveness has the power to erase any damage that has been inflicted, and forgiveness comes from a place of love. Because of this, I think it is pretty obvious that love is far more powerful than hate.
Love makes people delusional, so does hate.
Love makes people unite, so does hate.
Love makes people brave and courageous, so does hate.
Love makes people persevere till the end of time, while hate makes people persevere till they love something.
To that, there is a quote which says that you pay so much attention on hate that it is a love for hate.
Love prevails after all.
I think love is ultimately a more powerful force. Taking the example of WWII already mentioned, while hatred of Juden was one unifying force, that hatred was fueled and solidified by Hitler framing the Jews as a threat to Germany's greatness, so fierce loyalty and even love for country and home played a big part in his success in turning the Jews into scapegoats. Also, while the Holocaust is a tremendous example of hatred, it is also a place to look at some of the most amazing acts of love and kindness in history. Perfect "Aryan" Germans who would have nothing to fear from the Nazis risked their homes, jobs, and lives to hide Jews they had never met before and had no particular obligation to help. Even some people wore the Nazi uniform but did what they could do to fight against the Nazi cause. Jews shared food and hiding places in the midst of starvation and fear in order to help as many people survive the ordeal as possible. Without these acts of kindness and love, who knows how many people would have been killed during that time?
Fear, anger, and hatred all have another side that fuels them. Fear of the other comes from love of the self, love of tradition, of a perceived normality. You can get angry when something or someone threatens something/someone you love. You get worried or anxious when someone you love behaves in a way that you think is reckless or hurtful. At an individual level, it is often the people you once loved that you can end up hating the most, as indifference rarely produces such violent reactions.
Love is often the driving force for people to do daring things. Have you ever heard stories about what mothers or fathers have done to protect their children? Look at the volunteer organizations around the world where people work for free towards a goal they care about, to help save an animal/group of people/buildings/trees/whatever they love. Passion is often an extension of love, and passion drives people to do amazing things. How about, to use a current popular issue, the people risking their lives to simply support love for everyone in places where being homosexual is a death sentence or openly supporting gay marriage is illegal? Love makes people crazy, makes people angry, makes people afraid, amazed, productive, dangerous, and any number of emotions that drive people's motives. Love is a very, very powerful force.