This paper proposes that human culture has evolved from authoritative local premodernity through rational local modernity to the coming rational global postmodernity with diverse cultural types. Premodernity, modernity, and postmodernity are the cultural adaptations to the drastic social changes from the Agricultural, Industrial, and Information Revolutions. The cultural types analogous to biological species are the nine cultural types derived from the instinctive cultural type model based on the instinctive sociality trichotomy (individualistic, collectivistic, and interdependent) and the instinctive worldview trichotomy (territorial, connective, and competitive). Western culture originated from the Middle East and Greece has competitive worldview, while Eastern culture originated from India and China has connective worldview. Different cultural types have different perceptions, moralities, religions, politics, and economies. Currently, the world is the chaotic diverse global society where the cultural types clash. The coming postmodernity as rational global diversity is produced by the three rational global diverse systems. The rational global diverse system for the coming postmodern international politics is the three-tier international politics consisting of nations with geopolitical boundaries, the 12 regional communities with cultural-geographic boundaries, and the global international organizations without boundary. The rational global diverse system for the coming postmodern international trade is the trichotomic international trade containing free competitive, free connective, and fair protectionist international trades. The rational global diverse system for the coming postmodern common ground between religion and science is the cultural theology of trinity consisting of the transcendental, immanent, and imaginary cultural origins. The coming postmodernity as rational global diversity will bring rational order and peace among global diverse cultural types.