Ok. I'm not saying if we have one universal common language that all the sudden peace will break out everywhere and we'll all join hands kumbaya etc.
I'm saying that if you want to foster more peace and more brotherhood and so on that everyone being able to communicate in a common tongue is a good, perhaps even essential starting place.
Frankly I have always been and continue to be highly skeptical that the whole world will ever join as brothers/sisters in peace and blahblahblah. Seems mighty unlikely. However, maybe LESS war and more seeing each other as human beings could be managed... and a common language would help that happen IMO.