I quite like your way of thinking.
I believe as you appear to do that tolerance and respect for eachother is how world peace must begin and also that we must rely on peoples choices to be the correct ones, which is not always the case because of greed and personal motive. however with the correct measures people can be controlled (not in a derogitory way) and influenced by factors into making the 'right' decision.
what is possibly needed therefore, in my belief is a structure to politics that encourages people to make the right choices and makes it difficult for people to take a decision that will lead to war for personal gain, but will not hinder the ability to use force in protecting peace, which is the problem structures such as the league of nations had, as they did not have the power to stop someone from acting in the wrong way and their organization was very flawed.
we can see from previous attempts that the best results come when we work together. nothing is ever simple when discussing matters like these but if all focused on the same goal the power of unity between nations can accomplish a great deal if the leaders have the support of their people. This is the key to success. It is very much about the people putting faith in thier governments to work together. if the public are behind something it can be very successful. this has been shown time and time again throughout history. i do not pretend to be an expert, but i believe campaigns can always succeed with the correct support and the larger the problem the more support you need, but there are alot of people out there who want peace.