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China's leaders, beginning in the late 1970s, were able to transform themselves from devout Marxists into advocates of capitalist prosperity while still claiming they had the people’s best interests at heart. They maintained their power while shedding communism (in all but name) by offering material well-being in exchange for freedom. But in Iran, there is no such ideological fluidity. Religion — in the form of politicized Islam — is the foundation of the state and the sole source of clerical leaders’ legitimacy. Without a rigid Islamist ideology, the ayatollahs would become irrelevant. For Ayatollah Khamenei, China is a model to avoid and its journey from defiance to pragmatism a path to resist. He is therefore seeking to fully transform the Islamic Republic...