Backing up the argument:
Jerusalem has been revered for 3000 years by the Jewish people as the holy city above all other places on earth.
Jerusalem was never the capital of any Arab entity. Jerusalem has never served as a provincial capital under Muslim rule nor was it ever a Muslim cultural center. For Jews, the entire city is sacred, but Muslims mainly revere a site - the Dome of the Rock. During the 19 years Jordan ruled the Old City, no mention was ever made of making Jerusalem the capital of a Palestinian state. The fact that Jerusalem is disputed, or that it is of importance to people other than Jews, does not mean that others have an equal claim to the city.
Jerusalem is mentioned more than 700 times in the Jewish Bible. It is not mentioned even once in the Koran. The Western Wall in the Old City (the last remaining wall of the ancient Jewish Temple complex) is the object of Jewish veneration and the focus of Jewish prayer.
There is no precedent for an international city. The closest thing was postwar Berlin, when the four powers shared control of the city, and that experiment was a disaster. Additionally, no international group could be entrusted to protect the freedoms Israel already guarantees.
( See background )