Iran's Supreme Leader Ayatollah Ali Khamenei delivers a sermon during morning prayers for the Eid al-Fitr holiday, on July 18. (Handout/Reuters)

Ray Takeyh is a senior fellow at the Council on Foreign Relations.

The nuclear deal between the United States and Iran is already proving to be one of the most controversial arms-control agreements in history. All key aspects of the accord, from its enforcement mechanisms to its sunset clauses to its verification system, are subjects of contention. However, in the end, the viability of this deal rests not so much on technical formulations but on something as ephemeral as hope: the hope that once the deal’s essential restrictions fade in a decade, Iran will have been transformed into a responsible member of the global society; the hope that with the passage of time, the theocratic state will shed its revolutionary attire and become a reliable member of the international community. This is a big bet to place on one of the most peculiar regimes in modern times.

The notion that revolutionary regimes evolve to accept the legitimacy of the international order has many precedents. Indeed, most revolutionary states eventually concede their animosities for the sake of commerce and trade. Pragmatism often overwhelms rigid orthodoxy. Today, for instance, China’s foreign policy is hardly shaped by Mao’s call for Marxist mobilization against the world order. President Obama is seemingly convinced that once Iran’s interests are taken into account by the world and its coffers filled, it too will find the temptations of pragmatism difficult to resist. But this view displays little understanding of the clerical state and the unique role that religion plays in its self-image.

Unlike its revolutionary counterparts, the Islamic republic’s ideology is its religion. To be sure, this is a radicalized variation of Shiite Islam, but nonetheless religion is the official dogma. Revolutionary regimes usually evolve when their once-ardent supporters grow disillusioned and abandon their faith. It is, after all, simple to be an ex-Marxist, as this is a sign of intellectual maturation. But how easy is it for clerics to abandon a mandate from heaven? The hard-liners who dominate Iran’s unelected and most consequential institutions earnestly believe in their mission of salvation. Even the regime’s loss of popular appeal is immaterial to a political class that perceives its legitimacy as deriving from the will of God.

Since the inception of the Islamic republic, Iran’s clerical rulers have woven complex conspiracies about the United States. The United States is seen as a cruel imperialist power plundering the Middle East, and the themes of clashing civilizations and economic exploitation condition their international perspective. Then, Islamist assertions are never far behind, as the United States is also seen as a sinister source of cultural pollution seeking to delude young Muslims in the name of modernity. Thus, coexistence with the West can lead only to a loss of religious identity and submission to the United States’ global system of economic exploitation.

Although Western pundits and politicians are fond of invoking China as a model for approaching the theocratic regime, China’s evolution is precisely what Supreme Leader Ayatollah Ali Khamenei and his disciples are trying to avoid. A state that abandoned its revolutionary inheritance for the sake of trade and profits holds no attraction for men seeking to preserve their republic of virtue. Indeed, the Islamic republic’s foreign policy has long been fashioned to sustain its ideological character at home. The clerical rulers appreciate that their revolution can survive only if Iran remains isolated from subversive Western influences. A confrontational foreign policy rooted in anti-Americanism and anti-Zionism not only affirms the regime’s values but also ensures its continued estrangement from the West. To this elite, Obama’s promise of global integration is not an invitation but a threat.

The Obama administration may hope that a benign Iran at ease with the prevailing norms will emerge after the agreement expires. Khamenei, however, sees the future differently. “According to Koranic principles, fighting against arrogance and global imperialism is never-ending, and today, America is the very epitome of arrogance,” he insisted recently. The Islamic republic is an outlier that has defied the normative patterns of how revolutionary regimes evolve. A segment of the conservative elite, commanding key institutions of the state, has forged an aggressive foreign policy designed to preserve the ideological foundations of the regime.

The legacy of the nuclear agreement will not be a transformed Iran but a revolutionary regime possessing an elaborate nuclear infrastructure and seeking to dominate the Middle East. In the end, the shadow of this deal is likely to haunt the United States’ interests in the region for years to come.