When Turkey's foreign minister, Ismail Cem, resigned last month to form a new centre-left party, Turkey's overwhelmingly pro-European media acclaimed him as the man capable of defeating the popular moderate religious party in elections in November.
Unsurprisingly, the Islamic press didn't agree. But its criticisms took a strange form: "If the man they talk about is the same Ismail Cem Ipekci this nation has known since his days at the head of Turkish Radio and Television," wrote Turgut Emin in the conservative religious newspaper, Vakit, "then who would vote for him apart from his extended family?".
Run-of-the-mill invective? Not quite. For most Turks the references to "Ipekci" and his "extended family" clearly allude to Ismail Cem's alleged membership of one of Turkey's most secretive minorities, the Sabbateans, a heterodox Jewish sect.
Cem has long denied such claims, but he is only the latest target of a conspiracy theory that dates to the founding of the Turkish Republic in 1923. At its heart, two issues: the legitimacy of a secular regime in this mainly Muslim country, and the question of what it means to be a Turk.
"The Sabbateans have a monopoly over Turkish society," claims Mehmet Sevket-Eygi, columnist for the Islamic newspaper, Milli Gazete. "The Turks themselves live like the subject population of British India."
A vocal critic of what he sees as Turkey's excessive secularism, Eygi argues that secular measures "are always the will of Sabbateans because a real Turk, even an atheist Turk, would never do so much harm to Turkey."
Rifat Bali, an expert on Turkish Judaism, sums up bluntly: "the controversy boils down to the Islamists' belief that Ataturk himself was a Sabbatean." Sabbatean, he adds, has become a catch-all slur for any enthusiastic defender of Turkey's status quo.
Sabbateanism dates from 1665, when Ottoman rabbi Shabbetai Zvi proclaimed himself messiah. Forced by the sultan to choose between conversion to Islam or death, he converted.
After his death a community of his followers flourished in Salonica, once in the Ottoman Empire, now Greek. Muslims in appearance, they secretly practised a heterodox version of Judaism.
Tolerated under the cosmopolitan Ottoman empire, their difficulties began after 1923. Even before some 15,000 of them had moved to Istanbul as part of the massive population exchanges between Greece and Turkey, an anonymous pamphlet accused them of being "the greatest factor in the spreading of immorality, irreligion and contagious disease among Muslims".
In 1943 wealth taxes purportedly aimed at curbing war profiteering targeted Jews, Christians and Sabbateans. "The taxes came as a particular shock to the Sabbateans", says Leyla Neyzi, anthropologist and expert on Turkish minorities. "They identified strongly with the new secular Turkey and had largely broken their ties with a separate identity."
In 1998 the publication of Ilgaz Zorlu's best-selling book, I Am A Salonican, again stoked the fires of conspiracy. Born a Sabbatean, Zorlu recently converted to Judaism and sees it as his mission to defend Sabbateanism from extinction.
"All that remains of my community now is a sense of cultural difference, not enough to prevent its disappearance", he says. Zorlu believes Sabbateans must put aside what he describes as "their ingrained dislike of religion" and "convert en masse to Judaism."
According to Marc Baer, Turkish historian at Pittsburgh University, the most troubling thing about Zorlu's work is that "his claims about his community echo anti-Jewish and anti-Sabbatean myths popular in Turkey."
Zorlu's conviction that "Turkey's founders were all of of Sabbatean origin" has spurred religious newspapers to run headlines reading "Ataturk studied in a Jewish school" and "100,000 Sabbateans in Turkey."
It is now "common knowledge" that a media mogul and politicians ranging from the wife of the Prime Minister, Bulent Ecevit, through the recently resigned economy minister, Kemal Dervis, to the ubiquitous Ismail Cem, are of Sabbatean origin. "Zorlu has sold his soul to the fundamentalists", says Rifat Bali.
Zorlu is unrepentant. "The reason I don't accept Ismail Cem," he says, "is that he doesn't want to be a Jew." Leyla Neyzi's greatest concern is that anti-Sabbateanism "exists in diluted form in all walks of Turkish life". She describes the reactions of a pro-secular army officer she knows to a recent article about Ismail Cem on the popular Internet news site, Haberturk. The article alluded to Cem's supposed Sabbateanism.
"He told me there was much to admire about him, but that he was unsure of his origins," says Neyzi. She laughs: "Origins? Scratch a Turk, and there's no knowing what you'll get." For her, the real villain of the Sabbatean story is the creation after 1923 of a "Janus-faced Turkish national identity", both inclusive and exclusionary.
Convinced that the cosmopolitan cultural legacy of the Ottoman empire was a threat to the unity of the new republic, she argues, early Turkish republicans hitched ideas of universalist modernism to a concept of Turkishness based on Sunni Islam and an invented Turkish ethnicity. The Sabbateans' fate has been to swallow one and be bitten by the other.