The Surge of Converts to Judaism in Ancient Rome

The Surge of Converts to Judaism in Ancient Rome was written for More from Rabbi Landis.

Why did so many non-Jews, even from the ranks of the Roman elite like Queen Helena and Nero, convert to Judaism?

The conversion of Emperor Constantine of Rome to Christianity in 313 CE1 changed the course of world history. His conversion conferred Christianity as the Roman Empire’s national religion, beginning the process of it becoming arguably the world’s most dominant religion.

What is not widely known is that before this point Rome was inching ever closer to becoming a Jewish empire.

Surge in World Jewish Population

There are themes about the Jewish population of the Roman empire that are generally accepted by historians and scholars. In the first century of the Common Era, upwards of 10% of the Roman empire was Jewish with anywhere from 2 to 7 million Jews.2 This is quite remarkable. In comparison, consider the United States today where the Jewish community yields tremendous influence, yet only 2.4% of the country’s adults are Jews.3 The percentages of the Roman Empire were significantly greater.

If we look at the number of Jews in the world at the onset of the Babylonian Exile in 423 BCE we uncover something startling. Best estimates put the world Jewish population at that time at well under a quarter of a million.4 In a span of half a millennium, the Jewish people went from close to extinction to being a force to reckon within the Roman empire.

What could account for such a population explosion?

These were tumultuous times for the Jews. After the success of the Maccabees in the Hanukkah battles, the war with the Greeks went on for 25 more years. This was followed by several civil wars amongst the Jews, culminating in three major wars with the Romans. It was a time of a lot of Jewish bloodshed. Yet the numbers rose astronomically. Why?

Through mostly circumstantial evidence, scholars concluded that there was mass conversion to Judaism in the Roman empire at this time.5 There is no evidence, circumstantial or otherwise, that points to the Jewish community at this time proselytizing.6 How are we to understand such a rapid rise in the Jewish population through the avenues of conversion, without an active effort on the part of the Jewish community?

Bankrupt Polytheism

The Talmud gives us a better picture as to what was happing at this time.

Tractate Sanhedrin7 tells the story of Rav Ashi who referred to three idolatrous kings of Israel and Judah as “our colleagues.” That night, King Menashe (one of the three referenced) appeared to Rav Ashi in a dream and chastised him for presenting himself as their equal and showed him his vast knowledge of the intricacies of the Torah. Rav Ashi asked: if they were so wise, why did they engage in idolatry?

King Menashe responded, “Had you been there, you would have pulled up the hem of your cloak and run after me!” You have no clue how intense the desire to worship idols was in my day. You cannot relate and should not judge us by your present-day situation.

Pagan wooden idols.

This is a strange episode. King Menashe ruled the Southern Kingdom of Judah starting in 533 BCE and Rav Ashi was one of the main editors of the Talmud in 392 CE. The two were separated by almost a thousand years. What changed in those intervening years that took the enormous inner desire to worship idols that enticed King Menashe and reduced it to become an empty, laughable mode of thinking for Rav Ashi? None of us feel a tempting pull to get down on our knees and worship ancient idols on display in a museum. Why not?

The book of Nechemia,8 expounded by the Talmud,9 describes how the Evil Inclination to worship idols caused the First Temple to be destroyed, the righteous to be murdered, and the Jewish people to be exiled from their land. The governing body at the inception of the Second Commonwealth, known as the Men of the Great Assembly, was collectively aware of the desires amongst mankind to worship idols, as well as the past woes that it had caused. They wanted to make sure that their reboot of Israel would not be aborted by the same nefarious entities that caused the destruction of the First Commonwealth.

So the Men of the Great Assembly proclaimed three days of fast and prayer. At the end, they received a divine sign that their prayers were answered and the rampant inner desire to worship idols had been eradicated. This was around 350 BCE. From that point on in Jewish history, there is barely a mention of Jewish communities engaging in this spiritually destructive activity. It would take a lot longer for the flames of idolatry to be stamped out throughout other kingdoms where paganism was a national institution.

Perhaps we can now understand the climate in the Roman Empire that led to such an explosion of Jewish conversion. The populace had become keenly aware that idols of wood and stone held no sway over the world. The innate drive of an individual to find an authentic spiritual connection left many throughout the empire with a gaping void. They began to search, and many found the satiating waters of Judaism and converted.

Famous Converts

Before this point, there are very few mentions of converts to Judaism. From this point through the end of the Roman empire there are a plethora of examples, often from the aristocracy. The following is a shortlist of some of the most famous amongst them.

Shmaya and Avtalyon

The first famous converts we meet from this time are Shmaya and Avtalyon. Around the middle of the first century BCE, Shmaya was the Nasi or President of the Sanhedrin, the Jewish Supreme Court, and Avtalyon was the Av Beis Din or presiding Head Judge.10 Together, they were the spiritual leaders of Israel. What is most remarkable is that they were converts to Judaism11 and descended from Sancheriv, the Assyrian Emperor who is credited with conquering the Northern Kingdom of Israel and exiling 10 of the 12 tribes of Israel in 556 BCE.12

This shows a fundamental principle: Jewish leadership is a meritocracy. Here are two men of royal lineage who not only leave the comforts of their upbringing to embrace Judaism at a tumultuous time, but reach the greatest heights of the scholars of the generation. Shmaya and Avtalyon were the teachers of the great Hillel the Elder, one of the most famous rabbis of the Mishna. It doesn’t matter what a person’s beginnings are, with hard work and dedication, they can achieve anything in Jewish scholarship.

Queen Helena

Adiabene was a region in the Assyrian Empire, located where modern-day Erbil now stands in Iraqi Kurdistan, roughly 1,300 kilometers north-east of Jerusalem. Helena was the queen of this small Empire around the same time that Shmaya and Avtalyon led in Israel. After the passing of King Monbaz, their son Izates succeeded his father.13

When Izates was identified as crowned prince, he was sent away for his protection to Charax-Spasini, located in the modern-day Basra Governorate of Iraq, roughly 900 kilometers south-east of Adiabene. While there, he had fallen under the influence of Judaism. Unbeknownst to him, his mother was also being inspired by Jewish teaching.

Sarcophagus of Helene, Queen of Adiabene, from a collection at the Louvre Museum.

Upon returning home, mother and son learned of their synthesized religious interests. Initially, Queen Helena cautioned that they should keep their interest in Judaism a secret and urged her son not to take the convert’s final step of circumcision, lest it spark a rebellion in their kingdom. Izates at first heeded his mother’s warning, but later fully converted as a Jew. When Helena saw that the feared rebellion didn’t happen, she too fully embraced Judaism and even traveled to Jerusalem to bring sacrifices and valuable gifts to the Temple.14

Upon her passing, Helena was buried in Jerusalem. The tomb was discovered by archeologist Louis Felicien de Saulcy. The sarcophagus, assumed to be hers, found was later taken to the Louvre in France.15

Rabbi Akiva

The great Rabbi Akiva is one of the most famous Rabbis of Mishnaic times. He was born around 50 years before the destruction of the Second Temple (cir. 20 CE) and was one of the great Jewish rabbis in history. For his first 40 years he was an ignoramus, and then in the middle of his life he rose to become one of the greatest scholars and teachers of the Jewish people. He subsequently lost his entire academy of 24,000 students, yet did not give up. At the end of his life, he rebuilt everything with five students before being brutally assassinated by the Roman Emperor Hadrian in the aftermath of the failed Bar Kochba Revolt.

Rabbi Akiva’s father, Yosef, was a convert to Judaism.16 He was descended from Sisera, the great Canaanite General who tormented the Jewish people at the end of the second Millennium BCE. Sisera was finally subdued by Devora and Barak in 1087 BCE.17


At the beginning of the First Jewish-Roman War in 66 CE, Nero Claudius Caesar Augustus Germanicus, known simply as Nero, was the Emperor of Rome. It was he who sent Vespasian to put down the Jewish Revolt who, together with his son Titus, eventually conquered the country and destroy the Second Temple.18 Roman history records that in 68 CE a rebellion was mounted against Nero in Rome. He was declared a public enemy and sentenced to death by the Roman Senate in absentia. When Nero learned of his fate, he committed suicide.19

Jewish history tells a different story. The Talmud20 teaches that Nero came to Jerusalem during the war. In an attempt to see if fate would be on his side, he shot arrows in all four directions. All landed facing Jerusalem. In an attempt to explore further, he asked a Jewish child what verse in the Jewish Bible he was learning. The child responded by quoting the book of Ezekiel21 “And I will lay My vengeance upon Edom (Rome) by the hand of My people Israel.”

Nero concluded that “The Holy One, Blessed is He, wishes to destroy his Temple, and to wipe his hands with that man (referring to himself).” Nero then fled and was so inspired by the pseudo-prophecy that he received that he converted to Judaism. The great Rebbe Meir, whom much of the Mishnah is based on, is descended from him.

Imagine how embarrassing Nero’s conversion would be for the Romans. In the midst of a war, their Emperor suddenly defected to the other side. It makes sense that Roman history would seek to cover this up.

Onkelos the Convert

The Midrash Tanchuma22 tells us the unbelievable story of Onkelos the Convert. Onkelos was the nephew of Hadrian, the Roman Emperor referred to above who is infamous in Jewish history for the Bar Kochba War and subsequent anti-Torah decrees and bloodshed. When he decided to convert to Judaism, he feared his uncle’s wrath. As a pretext, he told his uncle that he wanted to travel to foreign lands to engage in business. Hadrian gave his nephew the age-old advice to “buy low and sell high.”

Onkelos then traveled to Israel to study Torah. After his conversion, he was asked by his uncle on whose advice he had done such a foolish thing. Onkelos responded that it was indeed the advice of his great uncle that motivated his conversion. There was no nation at that point as lowly as Israel. Surly their stock was destined to rise!

Hadrian sent a number of troops after Onkelos, but the newly minted scholar successfully convinced them all to convert to Judaism and the emperor stopped trying to bring his wayward nephew back. Onkelos went on to reestablish the ancient Aramaic interpretative translation of the Torah that now appears on the side of almost every Bible and is known as Targum Onkelos, Onkelos’ translation.

Embracing Judaism

Perhaps these famous converts are not the exception. There is circumstantial evidence that suggests that they were representative of the rule. The Roman elite began to see paganism as bankrupt. This led droves, especially amongst the aristocracy, to embrace Judaism. This also left the soil fertile for the eventual move of the empire towards Christianity. The religion of Jesus was a much easier pill to swallow as it offered at the time a version of ethical monotheism without the obligatory commandments like observing the Sabbath and circumcision.

The Rambam teaches us that the ascent of Christianity and Islam in the world are part of the Divine plan.23 Through these offshoot religions, central Jewish concepts and the Messianic ideal have spread to the four corners of the earth. This way, when the real Messiah finally arrives, the nations of the world will be as ready to embrace him, as will the Jews. May it happen speedily in our days.

  1. Lactantius, De Mortibus Persecutorum (“On the Deaths of the Persecutors”) ch. 48.
  2. Feldman, Louis H. “Conversion to Judaism in Classical Antiquity.” Hebrew Union College Annual, vol. 74, Hebrew Union College – Jewish Institute of Religion, 2003, pp. 115–56,
  3. Pew Reasearch Center, May 11, 2021, “Jewish Americans In 2020”
  4. Salo W. Baron, “Population,” Encyclopedia Judaica vol. 16, Second Edition, 2007 Keter Publishing House Ltd.
  5. Pasachoff, Naomi E.; Littman, Robert J. (1995). A Concise History of the Jewish People p.67
  6. Feldman. Ibid.
  7. 102b
  8. 9:4
  9. Yoma 69b, Sanhedrin 64a
  10. Rabbeniu Ovadia M’Bartenura, Avos 1:10
  11. Rambam, introduction to Mishna Torah
  12. Babylonian Talmud, Gitten 57b
  13. Josephus, Antiquities of the Jews, 20
  14. Babylonian Talmud, Baba Basra 11a
  15. French consulate opens disputed Second Temple site in East Jerusalem, Nir Hasson for Haaretz, 28 June 2019
  16. Babylonain Talmud, Sanhedrin 96b
  17. Book of Judges Chapter 4
  18. Josephus, War of the Jews III.1.3
  19. Suetonius, The Lives of Twelve Caesars, Life of Nero 47
  20. Gitten 56a
  21. 25:14
  22. Parshat Mishpatim, 5
  23. Mishna Torah, Laws of Kings and Wars aa:8

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