"Mojahedin-e Eslam" (The Assembly of Muslim Fighters) was one of the significant politico-religious organizations in Iran during the 1940s and 1950s. Due to the leadership of Shams Qanatabadi, the group’s historical importance has often the been overlooked by scholars. This study investigates the organization, which holds critical importance given its conflicting policies regarding the nationalization of the Iranian oil industry and its role in the 1953 coup d'état. A noteworthy observation is the group's lack of a consistent political trajectory. Although the assembly was among the primary supporters of Mohammad Mosaddegh and the oil nationalization movement, it eventually adopted a a passive and contradictory approach, partly influenced by its opposition to leftist tendencies. The shift in their political rhetoric—ranging from describing Dr. Mosaddegh as a "Savior" or "Reformer" to labels such as "Tyrant," "Modern Pharaoh," or "Dictator"—serves as compelling evidence of this transformation. Consequently, the primary objective of this research is to analyze the causes of the shift from convergence to divergence within this national-religious current. Relying on historical documents and archival sources, this study employs a descriptive-analytical method to address the following question: Why did the Mojahedin-e Eslam, despite their initial support for the nationalization of the oil industry, gradually adopt a cautious stance, eventually turning into open opposition? The findings indicate that the the assembly’s ideology, concerns regarding the influence of communism, political. rivalries with other factions, the socio-political turbulence during the nationalization movement, and Qanatabadi’s unbridled desire for power were the primary drivers of this significant metamorphosis