Conversions and proselytism

The history of Judaism is not only that of a people transmitted through descent: it is also, and constantly, the history of a threshold that men and women have crossed to enter the Covenant, or that others were compelled to cross in the opposite direction. Proselytism—that is, the voluntary aggregation of individuals from outside the community of Israel—and its reverse, forced conversion, together trace the shifting borders of an identity that claims to be at once ethnic and religious. To understand conversions is to understand how Judaism has thought of itself: open or closed, missionary or defensive, hereditary or elective.

Hebrew terminology conveys this complexity. The term ger originally designates the resident foreigner, then, in the rabbinic tradition, the convert. The word "gerim" is the plural of "ger," which in rabbinic usage designates a convert to Judaism. The classical distinction contrasts the ger tzedek, the proselyte of justice fully integrated, with the ger toshav, the resident foreigner observing the Noahide laws without embracing the entirety of the Law. This grammar of statuses reveals from the outset that Judaism elaborated, as early as antiquity, fine legal categories for thinking about belonging.

This volume traverses the ways of entering and leaving Judaism: the giyur of proselytes and its ritual, the great episodes of collective conversion in antiquity, the halakhic elaboration of the convert's status, then the drama of forced conversions—from the Visigoths to the Almohads, from the Spain of 1391 and 1492 to the Marranos and anusim. It seeks to distinguish, section by section, what the archive establishes from what memory transmits.

The idea that one could "become" a member of Israel appears late in the biblical corpus. The most emblematic narrative remains that of Ruth the Moabite, whose declaration "your people shall be my people and your God my God" (Ruth 1:16) would become, in rabbinic reading, the paradigm of the sincere proselyte. Tradition would make Ruth the ancestress of King David, conferring a foundational dignity upon conversion. This reading, however, belongs more to later interpretation than to any legal institution of the biblical era.

It is during the Second Temple period, and particularly during the Hellenistic and Roman era, that proselytism takes on an attested historical scope. The Jewish diaspora of the Mediterranean basin attracted sympathizers — the "God-fearers" (phoboumenoi ton theon) — gravitating around the synagogues without taking the step of full conversion. During the Second Temple period, Judaism attracted many converts and sympathizers, and some scholars have described this era as marked by notable proselytizing activity.

Two collective episodes dominate this period. The first is the conversion of the Idumeans (Edomites) under the reign of the Hasmonean John Hyrcanus, at the end of the second century BCE: according to Flavius Josephus, the Idumeans were compelled to adopt circumcision and the Jewish Law, which constitutes one of the earliest documented examples of conversion under political coercion — a paradox for a Judaism usually reluctant toward active proselytism. The second is the voluntary conversion of the royal house of Adiabene, in Mesopotamia, in the first century CE, of which Josephus recounts the hesitations of Queen Helena and King Izates concerning circumcision. These narratives, transmitted by a single source but widely credited, show the coexistence of voluntary conversion and imposed conversion.

The question of whether ancient Judaism was authentically "missionary" divides historians. Some, following a reading of Greco-Roman sources evoking the appeal of Jewish customs, see in it a proselytizing dynamic; others emphasize that aggregation occurred chiefly through passive attraction and marriage, not through organized preaching. Caution is required: the sources, whether polemical or apologetic, must be handled with circumspection.

Talmudic literature is what established the conversion procedure as tradition would lastingly know it. The tractate Yevamot of the Babylonian Talmud (notably at folio 47) describes how the candidate is received, and the small extra-canonical tractate Gerim records its details. The procedure rests on three pillars: circumcision (milah) for men, ritual immersion (tevilah) in the mikveh, and the acceptance of the yoke of the commandments (kabbalat ha-mitzvot), all before a rabbinical court of three judges (bet din).

In the talmudic era, the rabbis established a formal conversion procedure requiring circumcision for men, ritual immersion, and the acceptance of the commandments before a court. A characteristic feature of the rabbinical framework is the testing of the candidate: he is first dissuaded, warned of the persecutions that strike Israel, in order to test the sincerity of his approach. According to tradition, when a candidate presents himself to convert, he is first discouraged by being reminded of the sufferings of the Jewish people; if he persists, he is accepted and instructed in the commandments.

The fully admitted convert receives the title of ger tzedek, "proselyte of righteousness." The ger tzedek designates a convert of righteousness, that is, a non-Jew who has fully embraced Judaism. The conversion thus accomplished is conceived as a rebirth: the convert is legally compared to a "newborn child," a formula that carries considerable consequences regarding prior family ties and personal status.

Judaism furthermore distinguishes the full proselyte from the ger toshav, the resident alien. A distinction is made between the ger tzedek, the fully integrated convert, and the ger toshav, the resident alien who observes the Noahide laws without converting completely. This distinction allows rabbinical law to provide for a graduated belonging, recognizing a place for the pious non-Jew without requiring conversion of him.

Once admitted, the convert becomes a Jew in every respect: rabbinic law establishes the principle of equality, forbidding any reminder of his origin meant to belittle him. Yet his status carries legal particularities that the halakha has long debated. The chief one stems from the principle that "the convert is comparable to a newborn child" (ger she-nitgayer ke-katan she-nolad dami): legally, his former kinship ties are partly annulled, which raises complex questions regarding marriage, inheritance, and family prohibitions.

Certain formal restrictions persist in the classical tradition. According to a strict reading, a convert cannot hold positions of power reserved for a Jew "by birth" (for example kingship, according to an interpretation of Deuteronomy 17:15), and the daughter of a convert is subject to particular rules concerning marriage with a cohen. These provisions, which may seem in tension with the principle of equality, have been the object of interpretive efforts aimed at limiting their scope.

The sincerity of intent remains the crux of the debates. The question of whether a conversion carried out for an external motive — marriage, interest — remains valid has divided the authorities. The Talmud reports that conversions motivated by love or fear were sometimes recognized a posteriori, whereas the rigorist tendency demands a purely religious motivation. This tension still structures contemporary controversies.

In the modern era, the fragmentation of Judaism into movements has multiplied the debates. The various movements of Judaism — Orthodox, Conservative (Masorti), and Reform — diverge on the requirements of conversion, which raises the question of the mutual recognition of conversions. The question "Who is a Jew?" has become, particularly in the State of Israel, a major political and legal issue. Initiatives such as the Giyour Kehalacha court, founded in Israel to facilitate Orthodox conversions outside the Chief Rabbinate, illustrate the internal tensions. Giyur Kehalacha is a network of independent Orthodox rabbinic courts created in Israel to conduct conversions.

Beyond individual conversions, Jewish history preserves the memory of collective conversions whose magnitude belongs as much to founding myth as to attested event. The most famous case is that of the Khazars, a Turkic-speaking people of the Volga and Caucasus steppes, whose elite is said to have adopted Judaism around the 8th–9th centuries. The event is known through a correspondence attributed to Hasdaï ibn Shaprut, a Jewish dignitary of Cordoba, and to the Khazar king Joseph, as well as through Arabic and Byzantine sources.

This episode acquires a major literary and theological dimension through the Kuzari of Juda Halevi (12th century), a philosophical dialogue imagining the Khazar king questioning a Jewish scholar, a Christian, and a Muslim before choosing Judaism. The work, a monument of medieval Jewish thought, transforms an uncertain historical fact into an allegory of the superiority of Israel's revelation. Here, Memory and the archive answer one another without merging: the Khazar conversion is plausible in principle, but its extent, its depth, and even its institutional reality remain the subject of persistent scholarly debate, for want of sufficiently numerous first-hand sources.

Other collective conversions, more modest, mark the Middle Ages: individuals from the Christian or Muslim nobility, sometimes at the risk of their lives given the prohibitions against Jewish proselytism in Christian and Islamic societies. The case of Bodo, a deacon of the Carolingian court who became a Jew under the name Éléazar in the 9th century, is one of the few attested by contemporary sources. These individual trajectories, rare but documented, remind us that the attraction of Judaism never entirely faded, even in hostile contexts.

The reverse side of voluntary proselytism is the coercion exerted upon the Jews themselves to make them abjure. The history of forced conversions begins early. In Visigothic Spain, after the kingdom's conversion to Catholicism (Council of Toledo in 589), successive royal decrees — notably under Sisebut in the seventh century — imposed baptism upon the Jews, giving rise to a first population of converts suspected of secretly judaizing.

In the Islamic world, the great wave of persecution came from the Almohads, a rigorist Berber dynasty which, from the middle of the twelfth century, imposed upon the Jews and Christians of the Maghreb and al-Andalus conversion to Islam or exile. It was in this context that Maimonides' family left Cordoba. The crisis gave rise to an abundant halakhic literature on the conduct to be adopted: Maimonides himself wrote his Epistle on Persecution (Iggeret ha-Shemad), in which he distinguishes the outward profession of faith imposed under threat, which does not cause one to lose the status of being a Jew, from true inner denial. He maintains there that a Jew compelled to pronounce the Islamic shahada without believing it should not be equated with a voluntary apostate, and that he must, as soon as possible, flee to a land of religious freedom.

This jurisprudence of coercion (ones) is fundamental: rabbinic law recognizes that an act performed under threat of death does not fully engage the responsibility of its author. The principle of martyrdom (kiddoush ha-Shem, sanctification of the Name) applies to three cardinal transgressions — idolatry, murder, incest — but forced conversion to a monotheistic religion raised cases of conscience of great subtlety, which the medieval responsa examine case by case.

The most dramatic episode in the history of forced conversions unfolds on the Iberian Peninsula. The massacres of 1391, which began in Seville and engulfed all of Castile and Aragon, forced tens of thousands of Jews into baptism to escape death. Thus arose a vast population of "new Christians" (conversos), some of whom continued secretly to observe Jewish practices. These crypto-Jews were designated by the pejorative term marranos (probably from the Spanish marrano, "pig"), while Jewish tradition called them anusim, the "coerced."

The expulsion decree of 1492, issued by the Catholic Monarchs Ferdinand and Isabella, intensified the phenomenon: faced with the choice between exile and baptism, many Jews chose outward conversion. In 1497 Portugal underwent a massive and particularly brutal forced conversion, in which baptism was imposed without even offering the option of exile. It was to hunt down the clandestine Judaism of these converts that the Spanish Inquisition, established in 1478, and the Portuguese Inquisition deployed their repressive apparatus, judging the "crime" of Judaism among the new Christians.

The marranos posed to the halakha an unprecedented question: what is the status of a Jew baptized by force who transmits, sometimes over several generations and in the utmost secrecy, an impoverished and distorted practice? The majority of rabbinic authorities held that the anusim remained Jewish, while debating the terms of their reintegration. Many, having managed to flee to lands of refuge—the Ottoman Empire, Amsterdam, Salonika, the Maghreb—openly returned to Judaism, giving rise to the flourishing Western Sephardic diaspora. Others, who remained on the peninsula or emigrated to the colonies of the New World, perpetuated a crypto-Judaism whose traces survive into contemporary times. The return of these communities to normative Judaism frequently required a procedure of reintegration, or even a formal conversion for their descendants, when the matrilineal bond could no longer be established with certainty.

The history of conversions and proselytism reveals a Judaism stretched between two poles. On one side, a universalist dimension: the possibility offered to every human being to enter the Covenant, embodied by the figure of Ruth and by the meticulous rite of guiyour. On the other, a defensive dimension, shaped by centuries of persecution, which led Judaism to test at length the sincerity of candidates and to refrain from any active proselytism in societies where such proselytism was capital.

Forced conversions — Visigothic, Almohad, Iberian — constitute the tragic reverse of this history. They compelled the jurists of Judaism to elaborate a casuistry of coercion of great subtlety, distinguishing the extorted act from voluntary apostasy, and to invent a status, that of the anusim, so as not to abandon those whom violence had torn from the community. This twofold history — welcome and redemption, entry and return — shows that the boundary of Judaism was always a living membrane, permeable in both directions, and constantly renegotiated. Contemporary controversies over the recognition of conversions, in Israel as in the diaspora, directly extend these age-old debates: to define who may enter Israel is always to define what Israel is.