Yes Jerusalem is the oldest religion. But it does not have the greatest number of adherents, since it is exclusive to a certain tribe which originated somewhere in Ur or Haran. Christianity and Islam have billions of adherents, since the faiths are not based on a claim to a certain ethnicity. These two are the greatest religions today. Jerusalem belongs to Christians and Moslems as well. While the greater majority of Jews stayed away from Palestine since AD134, Christians and Moslems were building "facts on the ground"--the Church of the Holy Sepulchre AD335, the Dome of the Rock (which is the most prominent feature in panoramic views of Jerusalem) and the Al-Aqsa, 7th c. AD, plus many more churches and mosques built throughout the centuries. Thee are no relics of Jewish building except for the piece of wall built by King Herod the Arab.
U.S. State Dept. condemns 'vicious terrorist attack' that killed Palestinian infant (Haaretz)
from the article: Amr Moussa: Arabs must prepare alternatives to failing peace process