[Francis Fukuyama is a professor of international political economy at the Johns Hopkins School of Advanced International Studies and the author, most recently, of ''State-Building.'']

THIS year is the 100th anniversary of the most famous sociological tract ever written, ''The Protestant Ethic and the Spirit of Capitalism,'' by Max Weber. It was a book that stood Karl Marx on his head. Religion, according to Weber, was not an ideology produced by economic interests (the ''opiate of the masses,'' as Marx had put it); rather, it was what had made the modern capitalist world possible. In the present decade, when cultures seem to be clashing and religion is frequently blamed for the failures of modernization and democracy in the Muslim world, Weber's book and ideas deserve a fresh look.
Weber's argument centered on ascetic Protestantism. He said that the Calvinist doctrine of predestination led believers to seek to demonstrate their elect status, which they did by engaging in commerce and worldly accumulation. In this way, Protestantism created a work ethic -- that is, the valuing of work for its own sake rather than for its results -- and demolished the older Aristotelian-Roman Catholic doctrine that one should acquire only as much wealth as one needed to live well. In addition, Protestantism admonished its believers to behave morally outside the boundaries of the family, which was crucial in creating a system of social trust.

The Weber thesis was controversial from the moment it was published. Various scholars stated that it was empirically wrong about the superior economic performance of Protestants over Catholics; that Catholic societies had started to develop modern capitalism long before the Reformation; and that it was the Counter-Reformation rather than Catholicism itself that had led to economic backwardness. The German economist Werner Sombart claimed to have found the functional equivalent of the Protestant ethic in Judaism; Robert Bellah discovered it in Japan's Tokugawa Buddhism.

It is safe to say that most contemporary economists do not take Weber's hypothesis, or any other culturalist theory of economic growth, seriously. Many maintain that culture is a residual category in which lazy social scientists take refuge when they can't develop a more rigorous theory. There is indeed reason to be cautious about using culture to explain economic and political outcomes. Weber's own writings on the other great world religions and their impact on modernization serve as warnings. His book ''The Religion of China: Confucianism and Taoism'' (1916) takes a very dim view of the prospects for economic development in Confucian China, whose culture, he remarks at one point, provides only slightly less of an obstacle to the emergence of modern capitalism than Japan's.

What held traditional China and Japan back, we now understand, was not culture, but stifling institutions, bad politics and misguided policies. Once these were fixed, both societies took off. Culture is only one of many factors that determine the success of a society. This is something to bear in mind when one hears assertions that the religion of Islam explains terrorism, the lack of democracy or other phenomena in the Middle East....

SURPRISINGLY, the Weberian vision of a modernity characterized by ''specialists without spirit, sensualists without heart'' applies much more to modern Europe than to present-day America. Europe today is a continent that is peaceful, prosperous, rationally administered by the European Union and thoroughly secular. Europeans may continue to use terms like ''human rights'' and ''human dignity,'' which are rooted in the Christian values of their civilization, but few of them could give a coherent account of why they continue to believe in such things. The ghost of dead religious beliefs haunts Europe much more than it does America.

Weber's ''Protestant Ethic'' was thus terrifically successful as a stimulus to serious thought about the relationship of cultural values to modernity. But as a historical account of the rise of modern capitalism, or as an exercise in social prediction, it has turned out to be less correct. The violent century that followed publication of his book did not lack for charismatic authority, and the century to come threatens yet more of the same. One must wonder whether it was not Weber's nostalgia for spiritual authenticity -- what one might term his Nietzscheanism -- that was misplaced, and whether living in the iron cage of modern rationalism is such a terrible thing after all.