We want free will, but we also want a perfect world, the kind of world where everyone gets along and sings Kumbaya. World peace and all. We can't have world peace while having free will. World peace and free will occurring simultaneously is an impossibility. In order for world peace to happen, everyone would have to have the same beliefs. Free will cannot exist when everyone believes the same thing. In order for someone to have their own belief which is different from everyone else there has to be free will. Free will is what gives a person the ability to choose to believe a different belief than someone else. When everyone believes the same thing and there is no ability to have a different belief there is no free will.
By advocating for world peace, we are advocating for the elimination of free will. By advocating for free will, we are eliminating the option for world peace. As long as there is more than one person with free will, there will always be someone who believes something different. People who try to convert other people's beliefs are essentially attempting to suppress that persons free will along with their own. People who try to convert unbelievers into believing in their personal beliefs are only doing so to get to their version of heaven or peace without realizing that by stripping another of their free will, they are doing the same thing to themselves. Free will only works when everyone has it, not when you convert everyone into your belief.
As long as there is free will, there will never be world peace. The closest we could get to having free will and world peace is if the majority of us just keeping our beliefs to ourselves and not giving a shit about anyone else's beliefs. The majority of us not trying to convert people or control people just because they happen to believe something different. But with free will, there will always be those who believe they "need" to convert others' beliefs and there will always be those who believe that by suppressing someone's free will, that they are somehow saving them, from what they may not know.
Complete world peace is impossible as long as free will is around, but we can get close. We can live in a world filled with peace and harmony. All we need to do is stop trying to convert other people's beliefs and take away their free will. Stop wasting so much time and energy fighting and arguing over different beliefs. Focus on our own beliefs and trust that everyone else knows what they are doing with their own lives. Why do we need others to believe the same as us? Why do we care what anyone else believes? Life is so much easier when you just believe whatever it is that you believe and when you don't give a shit what anyone else believes. No need to defend beliefs. No need to fight over beliefs. No need to go to war over beliefs. No need to change anyone's beliefs. No need to do anything. Love and Peace!