The Accidental Judaism

 Judaism is commonly presented as a fortress — a tradition that survived millennia of persecution through internal coherence, divine protection, or sheer collective stubbornness. This image flatters both believers and their admirers. It is also historically misleading. Judaism, like every other set of human customs and beliefs, has been shaped at every turn by the civilizations surrounding it — borrowing, adapting, and transforming under external pressure as readily as any other tradition. The fortress was always more porous than it appeared.

I. The Afterlife Problem

Consider the afterlife. The Hebrew Bible has no meaningful doctrine of personal immortality. The dead descend to Sheol — a dim, shadowlike existence that is barely more than extinction, where nothing happens and nothing is felt. The Psalms are explicit: it is the living who praise God, not the dead (Psalm 115:16-18). The Ecclesiastes confirms the same pessimism: "there is neither work, nor thought, nor knowledge, nor wisdom in the realm of the dead" (9:10). This was not an oversight but a theology — one that distinguished Israelite religion sharply from Egyptian religion, which organized the entire life of the living around preparation for death.

The rabbis changed this. By the Talmudic period, Judaism had acquired a fully developed afterlife, a Paradise, a Hell, an immortal soul separable from the body — doctrines absent from the Torah and borrowed, unmistakably, from the competition. That competition was Christianity, which offered resurrection, salvation, and eternal life in terms so compelling that, as Paula Fredriksen has shown in When Christians Were Jews (2018) and Mary Beard in SPQR: A History of Rome (2015), even its early and modest success — slower and more contested than the triumphalist narrative suggests — was enough to force a response. The Pharisees had already moved toward belief in the hereafter, providing a bridge. The rabbis crossed it, adopting what they needed to remain competitive in a marketplace of salvation they had not created and did not control.

The Mishnah itself reflects this competitive pressure. Compiled under Rabbi Judah the Prince in the late second century, it presents itself as the authoritative continuation of the biblical tradition — oral Torah given to Moses at Sinai, transmitted in an unbroken chain to the rabbinical academies. This claim is, among other things, a polemical move: at precisely the moment when the New Testament was establishing itself as the legitimate heir to the Hebrew scriptures, the Mishnah asserted a rival legitimacy. The timing is not coincidental. Judaism and Christianity were defining themselves against each other simultaneously, each claiming to be the true continuation of what came before. The tradition that feels most ancient is often the one most recently constructed.

II. Augustine's Gift

The survival of Judaism in Western Europe adds a further irony. The standard account credits Jewish resilience — the synagogue, the text, the community. The more precise account credits Augustine of Hippo. His theological position, developed most fully in The City of God (413-426 CE) and in his treatises against forced conversion, was that Jews must not be forcibly converted or exterminated but preserved as living witnesses — their misery serving as confirmation of Christian truth, their survival as testimony to the authenticity of the scriptures Christians had inherited from them. This was not philo-Semitism; it was a theological instrumentalization of Jewish suffering. But its practical effect was protective. Every other group Rome and the Church defined as heretical was destroyed. The Cathars, the Donatists, the Manicheans — all exterminated. The Jews survived in Western Europe because a North African bishop decided they were theologically useful alive.¹

III. The Accident of Heraclius

The eastern story is stranger still, and less known. The Babylonian Jewish community — centered in the great academies of Sura and Pumbedita, producers of the Babylonian Talmud that became the foundation of normative Jewish practice — survived not through any internal strength but through a military accident and a political decision made by a Muslim caliph.

In the early seventh century, the Emperor Heraclius fought a long and eventually successful war against the Sassanid Persian Empire. Had he extended that victory, had Byzantine rule replaced Sassanid rule over Babylon and Persia, the Jewish communities of those territories would almost certainly have faced the fate of Jews under Byzantine rule elsewhere — forced conversion, persecution, or annihilation. Heraclius had already shown his disposition: in 629, after his victory over Persia, he ordered the forced conversion of Jews in Byzantine-controlled territories.² The Babylonian academies, the scholars, the manuscripts, the living tradition of Talmudic learning — all of it would have been at risk.

He did not succeed. The Islamic conquests of the 630s and 640s overtook the Byzantine expansion, and the Babylonian Jewish communities passed under Arab rule instead. What followed was not merely tolerance but active institutional support. Caliph Umar, confronted with competing forms of Judaism — Rabbinic, Sadducean, messianic, militant — made a deliberate political choice. Rabbinic Judaism, with its pacifist orientation, its scholarly authority, and its explicit teaching that dina de-malkhuta dina — the law of the kingdom is the law (Babylonian Talmud, Nedarim 28a) — was selected as the authorized form of Jewish life within the Islamic state. The Exilarch was honored; the academies were supported; messianic movements were suppressed with the cooperation of Rabbinic leadership. In exchange, the academies pledged their allegiance to the Caliphate and discouraged any Jewish nationalism that might destabilize it.³

IV. The Invention of Jewish Monotheism

The Gaonic period that followed — roughly the seventh through eleventh centuries, centered in Baghdad under Abbasid rule — was the crucible in which the Judaism we know was formed. The great legal codes, the systematization of Talmudic law, the standardization of liturgy and practice that gave subsequent Jewish communities their shared form: all of this happened under Islamic rule, in Islamic Babylon, supported by Islamic political structures.

But the Islamic influence went deeper than institutions. It reshaped Judaism at the level of doctrine and philosophical form. The historian David Lemler has described the tenth century in Baghdad as the moment of the "medieval invention of Jewish monotheism" — one of the "monstrous moments" in Jewish history, when an entirely new intellectual form was given to Judaism in response to a changed historical context.⁴

Before this period, the sages of the Talmud were believers, but they did not theorize the unity of God as an abstract philosophical concept. Strict monotheism — rigorous doctrine of the One, rationally demonstrated — was not a Jewish invention but an Islamic pressure. In Baghdad, where Jewish, Christian, Muslim, and Mutazilite thinkers competed in the same intellectual marketplace, each community was compelled to define itself through explicit doctrinal statements. The Islamic tradition of kalam — systematic rational theology — set the terms of the competition.

Saadia Gaon (882-942) was the figure who responded most decisively. His Emunot ve-Deot (Book of Beliefs and Opinions), written in Arabic, was the first work in the rabbinic tradition to place the concept of belief at the center of Jewish identity — and to treat belief not as opposed to knowledge but as its highest form.⁵ The existence of God, divine unity, the creation of the world: these were to be demonstrated by rational argument, not merely assumed as communal inheritance. Judaism was being reformulated, for the first time, as a religion of creed.

To legitimize this transformation, Saadia and those who followed him employed what Lemler calls a strategy of "naturalisation": claiming that these doctrines had always been present in the tradition, given at Sinai, but had never needed to be made explicit because they were self-evident. Only the crisis of the age — the competitive pressure of Islamic theology, the challenge of Karaism, the need to define Judaism against its rivals — had made the explicitation necessary. The innovation was disguised as retrieval. The tent was presented as the fortress it had never been.

This reinvention was so thorough that the concept of belief has been, ever since, inseparable from Jewish thought. Maimonides' Thirteen Principles of Faith, formulated two centuries later, are the direct heir of Saadia's project — and are themselves a medieval construction that many traditional Jews have since treated as ancient and immutable. The naturalisation strategy succeeded completely.

V. The Conclusion That Cannot Be Said in Polite Company

The argument can now be stated in full. The Judaism we know — its doctrine of afterlife, its creedal form, its strict philosophical monotheism, its institutional structure, its canonical texts — is the product of three external pressures operating across roughly a thousand years: Christian competition in the marketplace of salvation, Augustine's theology of Jewish witness, and Islamic intellectual and political civilization in Babylon and Baghdad.

Without Christianity's competitive pressure, the rabbis would not have adopted the afterlife and the immortal soul. Without Augustine, the Jews of Western Europe would likely have faced the fate of every other group the Church condemned as heretical. Without the Islamic conquests of the seventh century, the Babylonian academies would have fallen under Byzantine rule and almost certainly been destroyed. Without the Islamic intellectual environment of Baghdad, Judaism would not have been reformulated as a belief-based religion with a rational theology of divine unity.

No Islam, no Rabbinic Judaism. The formula is stark but the evidence supports it.

This is not a diminishment. Human institutions that last do so by adapting. The remarkable thing about Judaism is not that it resisted change but that it navigated change so successfully, so many times, under such varied pressures, while maintaining enough continuity to recognize itself across the centuries. The rabbis were not passive recipients of outside influence — they were skilled and creative adapters, absorbing what they needed, reframing it as inheritance, and transmitting it as tradition.

The rabbinical tradition considered Balaam the greatest prophet after Moses — a heathen, an outsider, a man hired to curse. It was he who saw most clearly what the tradition was: 'How goodly are your tents, O  Jacob, your dwelling places, O Israel' (Numbers 24:5). 

The fortress was always a tent. It took an outsider to say so.

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Notes

¹ On Augustine's doctrine of Jewish witness and its protective effects, see Jeremy Cohen, Living Letters of the Law: Ideas of the Jew in Medieval Christianity (University of California Press, 1999), chapters 1-2. For Augustine's own formulation, see Contra Faustum Manichaeum, XII, 23, and The City of God, XVIII, 46.

² On Heraclius and the forced conversions of 629-630, see Walter Kaegi, Heraclius: Emperor of Byzantium (Cambridge University Press, 2003), pp. 206-211. For the counterfactual argument regarding the Babylonian academies, see Ben and Rebecca Abrahamson, The Persian Compared with the Islamic Conquest of Jerusalem: Its Messianic Nature (unpublished paper).

³ On the Umar-Rabbinic accommodation and its institutional consequences, see Robert Brody, The Geonim of Babylonia and the Shaping of Medieval Jewish Culture (Yale University Press, 1998); and Mark R. Cohen, Under Crescent and Cross: The Jews in the Middle Ages (Princeton University Press, 1994), chapters 2-3.

⁴ David Lemler, L'invention du judaïsme. Comment les Juifs se définissent eux-mêmes (Albin Michel, 2025).

⁵ On Saadia Gaon and Islamic kalam, see Sarah Stroumsa, Maimonides in His World: Portrait of a Mediterranean Thinker (Princeton University Press, 2009), chapter 1; Henry Malter, Saadia Gaon: His Life and Works (Jewish Publication Society, 1921); and Saadia Gaon, The Book of Beliefs and Opinions, translated by Samuel Rosenblatt (Yale University Press, 1948).