No nation with separate and restricted boundaries—such as Persia, for instance—will exist. The United States of America will be known only as a name. Germany, France, England, Turkey, Arabia—all these various nations will be welded together in unity. When the people of the future are asked, “To which nationality do you belong?” the answer will be, “To the nationality of humanity. I am living under the shadow of Bahá’u’lláh. I am the servant of Bahá’u’lláh. I belong to the army of the Most Great Peace.” The people of the future will not say, “I belong to the nation of England, France or Persia"; for all of them will be citizens of a universal nationality—the one family, the one country, the one world of humanity—and then these wars, hatreds and strifes will pass away.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 18)
Unbridled nationalism, as distinguished from a sane and legitimate patriotism, must give way to a wider loyalty, to the love of humanity as a whole. Bahá’u’lláh’s statement is: “The earth is but one country, and mankind its citizens”. The concept of world citizenship is a direct result of the contraction of the world into a single neighbourhood through scientific advances and of the indisputable interdependence of nations. Love of all the world’s peoples does not exclude love of one’s country. The advantage of the part in a world society is best served by promoting the advantage of the whole. Current international activities in various fields which nurture mutual affection and a sense of solidarity among peoples need greatly to be increased.
(Universal House of Justice, The Promise of World Peace)