Today, one of the important issues in the Islamic world is the problem of cultural assimilation. The necessity of confronting cultural assimilation arises from the need to preserve the identity and spirit of the nation, which occurs through strengthening cultural foundations. The following article is written with the aim of examining the requirements of propagation in countering cultural assimilation from the perspective of the Supreme Leader and seeks to answer the question: What are the requirements of propagation in confronting cultural assimilation according to the Supreme Leader? This article attempts to address the aforementioned issues using a library-based and analytical-rational method. By examining various aspects, the findings indicate that, firstly, culture consists of three fundamental layers: worldview, character, and action, which can sometimes undergo cultural assimilation. Secondly, the solution to saving culture from assimilation and loss of identity lies in actively and dynamically engaging these three mentioned components. Thirdly, the institution of propagation and the scholars of religious seminaries possess complete potential for rescuing culture from identity loss across the three fundamental layers (worldview, character, and action). Fourthly, the role of the propagation institution in the worldview aspect is to strengthen and reinforce the foundational layer of culture in two stages: prevention and treatment; in the character aspect, it involves influence and reform; and in the action aspect, it encompasses both prevention and treatment.