The reliance of the Islamic Republic of Iran’s foreign policy on religion, both in policymaking and implementation, has created significant challenges over the past decades. This article aims to show the components and factors that led to the inclusion of religion (Shiite Islam) in Iranian foreign policy after the Islamic Revolution. The revolution itself breathed a religious spirit into Iran’s domestic and foreign policymaking. However, this return to religion went beyond the attitude arising from the revolution. It also resulted from a set of internal and external rules and norms that, by building a religious identity, defined the Islamic role in foreign policy and shaped behavioral patterns accordingly. This article focuses on identifying relevant components and argues that rules and norms, including political Islam, political independence, anti-arrogance at home, the end of the Cold War, liberation movements, Islamic fundamentalism, a transitional order, and a turbulent Middle East, have established religious identity in Iran's foreign policy. As a result, foreign policy behavioral patterns developed accordingly. The findings, based on a constructivist approach and interactive analysis of the environment shaping identity in foreign policy, show that while the Islamic Revolution played a fundamental role in making religion central to foreign policy, several rules and norms also contributed to this development.