Cosmopolitanism has a long history in Europe. It originates in late ancient Greece, and is carried forward in Christian theology. It encourages universal fraternity. Christianity does not love one's own nation only, it does not love sages and men of virtues only, it does not love one's close associates and compatriots only. Jesus did not teach that one should love his own nation or country. Christianity is not a self-respecting, self-centered, self-satisfied religion. In European history, especially after Napoleon conquered Europe, cosmopolitanism gave way to nationalism. The purpose of education was to train good citizens, not human beings. Many excellent Chinese Christians in early twentieth century expounded the broad-minded cosmopolitanism. They were against the narrow-minded nationalism or patriotism. Chinese culture and religion are essentially narrow nationalism and religion. Christians are not docile citizens under the feudal regime. This essay discussed the Judaism as a nationalistic religion. Judaism is both universalism and particularism in certain senses. But in essence, it is a nationalistic religion. Judaism is the preparation stage for Christian cosmopolitanism. Jesus broke the Jewish nationalist tie. This is a revolution in the history of human thoughts. In our times, if one only loves his own nation or his own church, he betrays Jesus' message. Our time is the time of Globalization. This is the realization of Cosmopolitanism of Christianity.