I have no country to fight for:my country is the earth and i m a citizen of the world.

world citizen has a variety of similar meanings,often referring ta a person who disapproves of traditional geopolitical divisions derived from national citizenship.
an early incarnation of this sentiment can be found in Diogenes of Sinope the founding father of the cynic movement in ancient Greece .of Diogenes(a Greek philosopher).

Albert Einstein described himself as a world citizen and supported the idea throughout his life,famously saying "nationalism is an  infantile is a measles of mankind."world citizenship has been promoted by distinguished people including Garry Davis,who lived for 60 years as a citizen of no nation,only the world.Davis founded the World Service Authority in Washington ,DC,which issues the World Passport to world citizen.
When people ask me where I come from I wish I could just reply “the world.” I have trouble defining where home really is and I’ve spent a considerable amount of time wondering if there is anywhere I truly belong, and I’ve come to the conclusion that I am “a citizen of the world.” It is as if I belong nowhere and everywhere at the same time. I feel like I belong nowhere because I was raised outside of my birth country, and therefore it doesn’t feel like my true home. Yet the country I was raised in can’t be my true home either because there I am considered an expatriate. On the other hand I belong everywhere. I am everyone.