Religion has progressed from a whole lifestyle, an integral part of an entire society and outlook on life, to a way to find oneself in a larger, supernatural universe. In ancient times, tribes had religion to support the tribal leadership by giving it an aura of mysticism (early divine right) and to explain the natural world (pseudo-science).
Little changed through the march from the Paleolithic through the Iron Age, except in the islands of humanism: Athens and Rome. With the end of Roman Civilization and the rise of a strong Roman Catholic Church, along with a rigidly-controlled feudal system that emphasized the divinity of maintaining's one place in the established order of things (monarchs placed on the throne by virtue of God, peasants deserving of nothing better than their position because humans are basically sinful and corrupt), religion was once again the only acceptable worldview and dominated the entire psychological/sociological environment.
The Renaissance, or rebirth, of the Roman world revived interest in science and toppled the Church, along with the absolute 'divine-right' monarchs. Eighteenth Century Liberalism found its peak in America with Jeffersonian ideals of individual liberties and a nearly modern view of civil rights, and found its nadir with the French Revolution and Robespierre's Reign of Terror. The modern European worldview owes its existence to those revolutions. The last European monarchies of note ended with the Great War, which also ended the last European absolute monarchy (the Romanov dynasty in Russia).
In Asia, divine monarchs lasted much longer: Not until the Twentieth Century were they toppled. In Japan, the disastrous Pacific War ended Hirohito's reign and killed the Japanese line of succession (one of the terms of Japan's surrender). In China, the Communist Revolution killed the Chinese imperial system and replaced it with a regime at least as bad in terms of human rights abuses: Maoist Communism.
Once religion had become divorced from everything else, people began to 'shop around' for faiths, causing a resurgance in religons that were direct lifts of ancient pre-Roman European and pre-Communist Asian faiths, collectively known as Neo-Pagansim. Some Asian religons approach the 'entire worldview' model of faith, but few practice them that way in the Western world. The last 'complete' religion of note may well be Islam, known as a source of horrible fanatacism and oppressive government. Atheism, the logical extension of Western Rationalism, is also becoming more and more popular.