Five hundred years after the Alhambra decree ordered the expulsion of Jews from Iberia, the Spanish government enacted a law offering Spanish citizenship to Jews worldwide. While presented as atonement for the horrors of the Inquisition, the citizenship offer was contingent on applicants documenting their Sephardic Jewish ancestry in Spain. However, not all candidates were practicing Jews, with many coming from converso backgrounds, for whom proving Sephardic ancestry was a bureaucratic challenge. Sabbateans (also Selanikli, or Dönme) present such group in Turkey. A group of Ottoman Jews in the 17th century Salonica joined the proclaimed messiah Sabbatai Zevi’s movement (thus, Sabbateans). When the Ottoman Sultan forced Zevi to convert to Islam, his followers followed suit. As a result of Zevi’s apostasy, continuous anti-Jewish stigmatization, and conspiracy theories that loomed on the community, Sabbateans publicly kept their ethnoreligious backgrounds a secret. Thus, for many young people of Dönme descent, Spain’s reparation law for Sephardim was a turning point: Their families having assimilated to the modern secular Turkish identity in contexts of stigmatization and conspiracy, many young people of Sabbatean descent learnt of their Jewish roots for the first time after 2015 with Spain’s citizenship offer. Although some may sense relief at releasing their “burden of silence” proving their Sephardic roots has proved a formidable challenge for many. This paper examines the parameters through which this group has re-framed their ethnoreligious ancestry in the context of legal citizenship claims. I use data from 22 months of ethnographic fieldwork and oral histories, to ethnographically trace how Sabbateans navigate labyrinthine and counter-intuitively secular bureaucratic body of knowledge through newly developed mechanisms of ancestry authentication. I argue that Spain’s citizenship offer provided a space for Conversos of Sabbatean descent to legally reclaim their Jewish-Iberian heritage. An unintended consequence of this was the revival of Sabbatean ethnoreligious ancestry among the youth, and the formation of a secular bureaucratic body of knowledge about Sabbatean history aimed towards ancestry authentication. Oral histories and interviews are rich resources for analyzing broader ideologies of hybridity and purity that permeate in understandings of ethnoreligious and national boundaries: the mixed character intrinsic to Turkish Conversos—Muslim yet Jewish, Greek yet Turkish, immigrant yet elite—shows the intricate play of binaries permeating nationalist semiotics. This research provides important insights for the study of Jewish-Muslim difference across the Mediterranean and for broader processes by which states regulate regimes of citizenship, ancestry, and belonging.