What we think and believe in our minds determines our actions, and so, the state of the world, and it's problems, are a perfect reflection of the thought processes of the people that inhabit it. The world's problems cannot be solved by trying to fix the outcomes and EFFECTS of our thought processes. It's the THOUGHT PROCESSES that must be changed. In other words, every individual has to change oneself in order to change the world. Rather than thinking that others need to change themselves to suit your opinions, you must change yourself, and those opinions. World peace cannot be forced upon anyone because force creates more conflict. It will happen when every individual is at peace within their own mind. Conflict in the mind creates conflict in the world. Peace of mind creates peace in the world, and it all starts with you. If you're not at complete peace in this very moment, and every other moment, it's because of the thought processes and emotions that are standing in the way, in this very moment, and every other moment. If you want complete peace for yourself, or for the rest of the world, simply let go of those thoughts and emotions, in this very moment, and every other moment. It's no more complicated than that, even if the ego/mind would like to think otherwise.
"There is no path to peace. Peace is the path." - Mahatma Ghandi