11 / “I RENOUNCE ALL JEWISH CUSTOMS”: The Forced Conversion Oaths

(This is Story 11 in our series "A Cautionary History: When Christians Turned Against Jews" 20 Stories to Combat Rising Antisemitism.)

There is a document that should make every Christian weep.

It is not a record of a massacre or a pogrom. The document itself was not a weapon of physical violence — but as you will see, the system it created most certainly was. And yet it may represent one of the most spiritually violent acts the Church ever committed against the Jewish people — because it was designed to make Jewish men and women hate themselves.

It is called the Abjuration of Judaism, and versions of it were used across medieval Europe for centuries. A Jewish person seeking baptism — whether by genuine conviction or under the crushing pressure of persecution — was required to stand before the congregation and recite a formal renunciation of Judaism. Not simply of theological disagreements. Of their own people. Their own history. Their own identity.

The language was not gentle.

In some versions, the convert was required to declare that they renounced Judaism “with my whole heart and soul.” They were made to curse the Passover — the very feast Yeshua himself celebrated the night before his crucifixion. They renounced the Sabbath — the sacred rest God commanded at Sinai and that Jewish families had observed for millennia. They were required to curse circumcision — the sign of God’s covenant with Abraham, which Paul himself never called worthless (Romans 3:1-2: “What advantage, then, is there in being Jewish or what value is there in circumcision? Much in every way! First of all, the Jews have been entrusted with the very words of God”).

And then came the language that is almost impossible to read.

In the Visigothic oath of abjuration — used in 7th-century Spain under King Recceswinth — Jewish converts were required to renounce Jewish food laws and Jewish fellowship, calling their former practices an abomination. Many times, they were required to eat pork as part of the ceremony — meat that never touched the mouths of Jesus or his disciples. To eat it publicly, before a watching congregation, was to perform the desecration of everything your family had honored before God. And even if someone argues that all food is permissible, the New Testament is equally clear that violating one’s conscience is itself a sin — Paul devotes an entire chapter to this in Romans 14.

Some versions of the “confession” required the convert to refer to prior Jewish observance in language that translated roughly as filth or vomit. The Visigothic legal code preserves the actual prescribed words: “I promise that I shall never return to the vomit of the Jewish superstition.” This was not informal rhetoric. It was legally required liturgy — spoken by Jewish mouths, under compulsion, and presented as an act of Christian faith. But nothing done under compulsion resembles faith.

They were not asked to embrace Jesus. They were required to desecrate their own heritage as the price of admission.

How Did This Happen?

To understand how the Church arrived here, we need to understand the world these oaths emerged from. By the 7th century, the institutional separation of Christianity from its Jewish roots — a process we will examine more closely in Story 13 with Constantine and the Council of Nicaea — was already centuries old. Jewish practice had been officially framed not as the foundation of Christian faith, but as its enemy.

Theologians had argued for generations that Jewish observance after the coming of Messiah was not merely unnecessary — it was dangerous. Jerome, the great 4th-century Bible translator, called the synagogue “a brothel.” John Chrysostom, one of the most celebrated preachers in Church history, delivered a series of sermons in Antioch in 387 AD, titled Against the Jews (in Greek, Adversus Judaeos)—eight sermons of stunning ferocity that warned his congregation not to attend synagogue services or celebrate Jewish festivals.[1] He called the synagogue “a dwelling place of demons.” He called Jewish people “lustful, insatiable, greedy, dishonest bandits.” Paul urged the Gentiles to provoke Israel to jealousy. Chrysostom turned the descendants of Abraham into villains to be hated. He wrote:

These were not fringe voices, but the Church Fathers, who were among the most respected theologians of their age. Their words shaped how clergy thought about Jewish people for centuries — and that thinking eventually produced the conversion oaths.

By the time the medieval Church formalized the abjuration rituals, the logic was internally consistent, however spiritually catastrophic: if Judaism was spiritually worthless and potentially demonic, then a true conversion required not just accepting Jesus but publicly destroying any attachment to the Jewish world. The convert had to prove their sincerity by denouncing their own mother.

What This Did to People

We must pause and feel the weight of what was being asked.

Imagine being a Jewish man in 10th-century France. Perhaps you have come to genuine faith in Yeshua — your Messiah, born of your people, the fulfillment of your own Scriptures. And you are told that before you can be baptized, you must stand before the church and declare that your grandmother’s Sabbath candles were an abomination. That your father’s Passover Seder was vomit. That the community that raised you, loved you, buried your ancestors — that all of it was filth. Yes, this was the Church’s version of Jewish evangelism!

And if you refuse? In many times and places, refusal meant exclusion at best and violence at worst. During periods of forced conversion — and there were many — the oaths were not optional. They were survival documents.

The Church did not offer Jewish people Jesus. It offered them a Jesus who despised everything they were.

The Irony the Church Missed

Here is what makes this theologically devastating, not merely historically sad: Yeshua himself was a Torah-observant Jewish man. He kept the Sabbath. He celebrated Passover. He was circumcised on the eighth day (Luke 2:21). He declared that he came not to abolish the Torah but to fulfill it[3] (Matthew 5:17). Paul — who preached the radical grace of the gospel to Gentiles across the Roman world — never stopped identifying as a Jewish man: “I am an Israelite myself, a descendant of Abraham, from the tribe of Benjamin” (Romans 11:1).

The faith these oaths were defending was born in a Jewish womb, nursed on Jewish Scripture, and carried into the world by Jewish apostles. It was the Hebrew prophets who spoke of his coming. To require a Jewish person to curse their Jewishness as a condition of following the Jewish Messiah was not faithfulness. It was a desecration of the gospel itself. It was the exact opposite of what James and the apostles envisioned in Acts 15 when they did not require Gentiles to embrace Jewish liturgical life. And it was something that never entered the mind of the Jewish apostles when sharing the gospel with other Jewish people.

The New Testament never asks this. Paul — who understood better than anyone the relationship between Judaism and the new covenant — wrote with anguish, not contempt, about his own people. He declared he could wish himself cut off from Messiah for their sake (Romans 9:3). He called the Jewish people “beloved for the sake of the patriarchs” (Romans 11:28). He asked Gentile believers to consider themselves not the replacement of Israel but “grafted in” to her (Romans 11:17-18) — and warned them explicitly not to be arrogant toward the natural branches.

Faces Behind the Oaths

These were not abstractions. They were inflicted on real people, in real places, with real consequences.

Nearly 1,000 years before the Spanish Inquisition, in Visigothic Spain in 616 AD, King Sisebut issued a decree requiring all Jews in his kingdom to accept baptism or face expulsion. Tens of thousands were baptized — not by conviction, but by royal command. Each one was required to recite formal renunciations of Jewish practice.

A Jewish father who had taught his son to read Torah now had to stand before a priest and declare that Torah observance was an abomination. Many complied publicly and wept privately. Many continued to observe Jewish practices in secret — which is precisely how the crypto-Jewish communities we examined in Story 7 came to exist centuries later in Portugal. But the authorities knew this was happening, and the penalties for being caught were savage.

Under King Recceswinth, Jews who practiced the rites of their faith were to be beheaded, burned, or stoned to death.[4] And in one of the most chilling details of this entire era, converted Jews were required to swear that if any transgressor were found among their own people, “he shall be burned, or stoned to death, either by ourselves, or by our sons.”[5] A Jewish father, forced to convert, is legally obligated to execute his own son for lighting Sabbath candles.

Those who were caught returning to Jewish practice were described in church records as relapsing — the same word we use today for an addict falling back into destructive behavior. One 14th-century inquisitor’s record put it even more graphically, describing a baptized Jew who returned to Judaism as going back “like a dog to his vomit.”[6] The same language from the conversion oaths — now applied to the person being hunted down and killed for practicing the faith of their fathers. The forced oath did not produce Christians. It produced survivors — and it turned survivors into potential executioners of their own children.

In the Frankish kingdom in the 9th century, Archbishop Agobard of Lyon — a man considered a theological reformer in his time — campaigned relentlessly against Jewish religious freedom.

• He pushed for Jewish children to be taken from their parents and baptized without consent. 

• He wrote treatises arguing that Jewish worship was so spiritually dangerous that Christian servants should not be permitted to eat food prepared by Jewish hands.

• When Jewish people were baptized in his diocese, the renunciation formulas used under his influence required them to declare that they approached the faith “fleeing the blindness and superstition” of their former lives as Jews.

Why Wait till We Get to Jerusalem?

Perhaps the most heartbreaking cases come from the period of the Crusades, which we examined in Story 2. The Crusaders had set out with a holy mission: to liberate Jerusalem from Muslim control. But as they marched through the Rhineland, a deadly logic took hold. If the purpose of the Crusade was to defend Christendom against its enemies, why wait until reaching the Holy Land? The Jews living in the cities along their route — Speyer, Worms, Mainz, Cologne — were right there. They could be dealt with now.

The reasoning, such as it was, went something like this: We are marching to reclaim the land where Christ was crucified. The people who crucified him are living among us. Convert them, or kill them. Why travel a thousand miles to fight the enemies of Christ when the enemies of Christ are our neighbors?

Baptism or Death—You Choose!

What followed was a killing spree dressed up as evangelism. As crusading mobs swept through the Rhineland in 1096, thousands of Jewish people were given an immediate choice: baptism or death. Those who chose baptism to survive — often watching family members die around them — were subsequently required to formalize their conversion with the renunciation oaths. Having already lost everything, they were then compelled to stand before the Church and declare that what they had lost was worthless.

And here the forced conversion oath revealed its true nature. These were not people persuaded by the gospel. They were people who had seen their fathers killed and their children threatened. The oath they recited was not faith. It was ransom.

Some of the Jewish chronicles from this period record that survivors who had been forcibly baptized this way later made their way back to Jewish communities and underwent ritual re-entry, accepting whatever consequences came with it. They had recited the words. They had never believed them.

And this is perhaps the most telling detail of all: the Church knew many of these conversions were not genuine, and demanded the oaths precisely because they knew. The oaths were not a pastoral tool. They were a mechanism of control — designed to make a return to the Jewish community as psychologically and spiritually costly as possible.

You might wonder how the Church could do this. The answer is that by this point, the Church was no longer primarily building the kingdom of God — it was enforcing political loyalty. The Great Commission calls us to make disciples through proclamation and love (Matthew 28:19). What happened in Visigothic Spain was the opposite: coercion in the place of conviction, fear in the place of faith, and political conformity dressed up as salvation. When the Church trades the gospel for power, the people who suffer most are always the most vulnerable — and in medieval Europe, that meant the Jews.

Satan’s Strategy — and Ours

Step back from the individual stories, and a pattern becomes unmistakable. In every chapter of this series, we have seen the same spiritual logic at work: isolate the Jewish people, degrade their identity, sever them from their own heritage, dehumanize them, and make the name of Jesus a source of terror rather than salvation. We have said this before, and it bears repeating — this is not simply human cruelty. This is a strategic assault by the one Jesus called “the father of lies” (John 8:44). Satan hates the Jewish people because he hates the Jewish Messiah. And he knows that God’s plan for the redemption of Israel runs through the Church. A Church that crushes Jewish identity rather than honors it has been weaponized against God’s own purposes.

The forced conversion oaths were not an anomaly. They were the logical conclusion of centuries of teaching that told Christians the Jewish people were spiritually subhuman — that their practices were demonic, their identity a liability, their heritage something to be burned away rather than fulfilled in Messiah. That teaching did not come from the New Testament. It came from men who had drifted so far from the Jewish roots of their faith that they could no longer recognize them.

You might be wondering — as a Gentile believer, where do I fit in all of this? The answer is closer than you think.

Yeshua is returning. Revelation 5:5 calls him “the Lion of the tribe of Judah, the Root of David.” Zechariah 14:3-4 tells us his feet will stand on the Mount of Olives — in Jerusalem, in the land of his people. Revelation 19:11 and following describes him coming as a warrior-king to defend the very nation these oaths were designed to destroy. He is not returning as a Roman. He is not returning as a Gentile. He is returning as a Jewish king to a Jewish city to rescue a Jewish people.

And he is bringing his Bride with him.

Which means the question every Gentile believer must answer is not “Does this have anything to do with me?” It has everything to do with you. The question is: when he arrives, which side of history will you have been on? Will you have stood with his people — or looked the other way while the world pressured, coerced, and destroyed them? Many scholars believe that the question that divides the sheep and the goats, just after he returns, standing in Jerusalem and all this glory, is going to be: how did you treat the least of my brothers—the Jewish people?

The Church was given a mission to make Israel jealous (Romans 11:11) — to so beautifully embody the Jewish Messiah that his own people would want to know him. Every forced conversion oath was a betrayal of that mission. Every act of love toward the Jewish people today is a fulfillment of it.

When he returns, those who forced his brothers and sisters to curse their own identity in his name will have to answer for it. The oaths were spoken in the name of Jesus. Nothing could be more of a breach of the commandment not to take God’s name in vain.

We get to be different. We get to be the generation that looks at this history with clear eyes, grieves what was done, and loves the Jewish people the way Paul loved them — with the kind of love that would cost us something.

That is what the gospel actually asks.

Dr. Ron Cantor

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[1] Commentators have pointed out that rank-and-file believers were very much attracted to the Jewish roots of the New Testament faith — attending synagogues, observing Jewish festivals, and listening to the shofar on Rosh Hashanah. It was precisely this that Chrysostom and other Church Fathers were reacting against, driven in part by institutional rivalry with the synagogue and a determination to forge a separate Christian identity — even at the cost of severing believers from the very roots of their faith.

[2] John Chrysostom, Adversus Judaeos (Against the Jews), eight homilies delivered in Antioch, 386–387 AD. The sermons are available in English translation at tertullian.org/fathers. Chrysostom is venerated as a saint in both Catholic and Eastern Orthodox traditions. His sermons were used as model homilies in seminaries for centuries after his death.

[3] In rabbinic thought, to "fulfill" the Torah meant to interpret it correctly — as opposed to “abolishing” it, which meant misinterpreting it. This is precisely what Yeshua does throughout the Sermon on the Mount (Matthew 5–7). When he says “You have heard it said... but I say to you,” he is not replacing the Torah but interpreting it at its deepest level — showing, for example, that the prohibition on murder extends to anger, and that the prohibition on adultery extends to lust. He is functioning as a rabbi, not a reformer. This understanding further exposes the irony of requiring Jewish believers to curse their Torah-observant heritage in the name of a Messiah who never abandoned his own.

[4] Jewish Encyclopedia (1906), article “Visigoths,” jewishencyclopedia.com/articles/14710-visigoths. The Jewish Encyclopedia, though over a century old, remains a standard reference work compiled by leading Jewish and academic scholars of its era.

[5] The full text, which is worth reading, of the Toledo Memorial presented to King Recceswinth (654 AD) is preserved in the Visigothic Code (Leges Visigothorum) and translated at the Center for Online Judaic Studies: https://cojs.org/the_visigothic_code-_the_jews_of_visigothic_spain_-654-681.  

[6] Cited in Elisheva Baumgarten, “On the Language of Conversion: Visigothic Spain Revisited,” drawing on the Inquisition Register of Bishop Jacques Fournier of Pamiers (1318–1325), one of the most complete inquisitorial records of the medieval period. Available via ResearchGate: http://researchgate.net/publication/270609988 .