Slowly but surely Iran's clerical regime is collapsing. The recent arrest of 13 Iranian Jews on charges of espionage is an ugly reminder that the fall will likely be neither pretty nor peaceful. By attacking their own helpless Jews, the ruling mullahs vicariously strike at larger, more dangerous targets -- Israel, the United States and secular democracy, the most pernicious Western idea gaining ground in the Islamic Republic.

These arrests ought to encourage us to reassess the moderation and mission of Iranian President Mohammed Khatemi. Many Iran-watchers have tried to give Khatemi the benefit of the doubt. This espionage case has generally been depicted as a byproduct of the power struggle between Khatemi and the hard-line revolutionary leader Ali Khamenei. Alternately seen as powerless or judiciously playing a long-term game against the leader's stronger forces, Khatemi has so far escaped severe criticism for Iran's increasing internal repression.

Though serious differences divide the president and the revolutionary leader, this Western generosity toward the Iranian president is increasingly misplaced. Concerning the "Jewish menace," Iran's radical clergy certainly isn't divided. Though Martin Indyk, assistant secretary of state for Near Eastern affairs, may "find it hard to reconcile . . . Khatemi's words [about the rule of law]" with the espionage charges, Khatemi isn't likely so conflicted. Conspiracy defines and debases politics in the Middle East, and one of the the most common and visceral conspiracy theories in Iran is of an internationalist Jewish cabal trying to humble the Muslim world.

The Iranian "clerical left," where both Khatemi and Khamenei cut their intellectual teeth in the 1970s, is wildly anti-Zionist. In public, President Khatemi has referred to Israel as a "racist, terrorist regime." In private, where Iranians often mercifully ignore their public utterances, he is reputed to be no less adamant in his attacks against the Jewish state and its ability to control the United States.

Far more Westernized than the traditional clergy, the clerical left has been more open to the good and the bad in Western thought. A fascination with Karl Marx or John Locke can rest side by side with a belief in the worst Russian antisemitic tracts. It is only through weighing these apparent contradictions that we can have some idea of where Iran is going.

Much has been made of Khatemi's call for a "dialogue of civilizations." Some observers have seen Khatemi's words presaging a thaw in the U.S.-Iranian confrontation. Atypically for a mullah, Khatemi is fascinated by the Western idea of freedom and acknowledges the West's glorification of individual rights. His speeches, pamphlets and books refer constantly to individual liberty and its hold on the human soul. Unlike most radical revolutionary clerics, who sound like angry 1960s Left Bank intellectuals, Khatemi is a fairly serious student of Anglo-American political thought.

But Khatemi's curiosity has limits and an ulterior purpose. Freedom for him must have a divine mission, to avoid the West's spiritual misery and rot. Democracy without divinity devolves into passion, greed and disbelief. Probably no less than Khamenei, Khatemi views Western culture -- especially the American cutting edge -- as a cancer on the Muslim politic. Unlike the revolutionary leader, Khatemi knows the Islamic revolution must adapt to certain modern realities to survive. Like Thomas Aquinas, however, he believes that reason, faith and a holy law can and must be fused together.

In his CNN interview, the president alluded to the pilgrims, America's most zealous religious immigrants, as his ideal. English Puritans exercised their liberty to found colonies uniting church and state. For a devout Muslim, the parallel with the prophet Muhammad's early community in Arabia is obvious.

In his heart, Khatemi may want the Iranian Jews set free, his sense of mercy overcoming his anti-Zionist zeal. But we should not be misled by the mullah's apparent kindness. Khatemi clearly understands how the West's most cherished ideas can be devastating to his Islamic ideals. The Ayatollah Khomeini, not Locke, is the cleric's primary role model.

As more liberal dissidents, minorities and disenchanted clerics find themselves harassed and jailed by Iran's hard-liners, we in the West should be cautious in seeing Khatemi as a good man who would do better if he could. Such consideration on our part -- particularly if effected through quiet diplomacy -- could be lethal to Iranians who simply want to enjoy the freedoms that Americans consider their birthright.

The writer is a former Middle East specialist with the Central Intelligence Agency.