"Don't think of being an American citizen, but a global citizen". This thought of reverse nationalism is going to take us towards a world communitarian society, in which NGO (non governmental organizations) will ultimately control every aspect of our life, enforced by the government of your choice. When a global government is installed, there will be nowhere you can go without the long arm of the United Nations encumbering your life.
Am I properly getting this across to you? The constitution governs how "we the people" want our nation to be run. We can't give over our sovereignty to a world government and still believe we have the capacity to govern.