The Pahlavi government used the modern discourse of secularism as an element of identity and legitimacy to consolidate its power and implement its domestic policies. Although the emphasis on the discourse of secularism began during the Pahlavi era, it remained an unfinished project due to the occupation of Iran and the decline of the Pahlavi era. However, the Pahlavi era, especially after the land reforms and the increase in oil revenues, attempted to revive it in the 1960s. This discourse was formed in a political and social context in which religion and tradition formed the basis of the discourse of society, and the Pahlavi government was forced to reject and eliminate the competing religious and traditional discourse in order to establish a new semantic order. The Pahlavi government failed to implement this project, and the victory of the Islamic Revolution in Bahman 1978 is considered the defeat of the discourse of secularism in Iran. Accordingly, the question arises: Why did the second Pahlavi dynasty fail to establish and hegemonize the discourse of secularism, and did the discourse of secularism fail in its confrontation with religious discourse? Accordingly, this article, citing Laclau and Mouffe's discourse theory, tests the hypothesis that although the discourse of secularism attempted to introduce religious and traditional discourse as its other and to devalue it through its negative representation, it failed to become a hegemonic discourse due to its lack of adaptation to the political and social contexts of Iranian society on the one hand and the ability of the rival discourse to recover itself on the other, and consequently collapsed with the Islamic Revolution of 1979.